Pre-mrna splicing screening assay

ABSTRACT

The present invention relates to a method for screening agents which modulate the binding of CDC5L to PLRG1, or specified fragments thereof, and agents identified using such an assay. The present invention also provides small peptides capable of inhibiting pre-mRNA splicing. Such agents are candidates for use in the treatment of, for example, cancer, or fungal infections.

[0001] The present invention relates to a method for screening agents which modulate the binding of CDC5L to PLRG1, or specified fragments thereof, and agents identified using such an assay. The present invention also provides small peptides capable of inhibiting pre-mRNA splicing. Such agents are candidates for use in the treatment of, for example, cancer, or fungal infections.

[0002] Pre-mRNA splicing occurs in the eukaryotic cell nucleus through a process that involves the removal of non-coding sequences (introns) in the pre-mRNA and the joining of adjacent or alternate coding sequences (exons) to produce mature mRNA. The splicing reaction takes place via a two-step transesterification mechanism involving nucleophilic attacks of phosphodiester bonds and creation of new bonds resulting in the formation of mature mRNA that is then exported to the cytoplasm for use in protein synthesis (for review see Staley and Guthrie, 1998). Splicing is catalysed by a large ribonucleoprotein complex made up of over a hundred proteins called the spliceosome. The spliceosome complex contains four ribonucleoprotein (snRNP) particles (U1, U2, U5, and U4/U6), each of which contains the corresponding snRNA and a set of specific and common proteins (Kramer, 1995; Kramer, 1996; Will and Lurhmann, 1997). The complex also contains multiple non-snRNP associated proteins that are essential for spliceosome assembly and catalysis (Will and Lurhmann, 1997; Staley and Guthrie, 1998). Spliceosome assembly involves the sequential association of the snRNP particles and other proteins onto the pre-mRNA substrate prior to catalysis (reviewed in Reed and Palandjian, 1997).

[0003] Several recent studies have suggested that both the human proteins CDC5L and PLRG1 and their respective homolgues in yeast are associated with pre-mRNA splicing factors (Neubauer et al., 1998; Tsai et al., 1999; McDonald et al., 1999; Burns et al., 1999; Ajuh et al, 2000). The human proteins' possible involvement in pre-mRNA splicing was first suggested when both proteins were identified by mass spectrometry in purified spliceosomes assembled on adeno-pre-mRNA in vitro (Neubauer et al., 1998). However, other cellular roles for CDC5L have also been proposed; for example, it has been suggested that CDC5L may also be involved in transcription because of sequence similarities in the amino terminus domain of the protein with the proto-oncogenic transcription factor, c-Myb (Ohi et al., 1994; Bernstein and Coughlin, 1997). Also, the A. thaliana homologue of this protein (AtCDC5), when over expressed in S. pombe, can complement a growth defective phenotype of an S. pombe CDC5+ temperature-sensitive mutant. A sequence-specific DNA binding activity has been reported for AtCDC5 (Hiriyama and Shinozaki, 1996). A possible role for this protein in the regulation of the cell division cycle was observed in a genetic screen of S. pombe for cell division cycle mutants. The study indicated that the CDC5+ gene encodes an essential protein and that the gene's function may be necessary in the G2 phase of the cell cycle (Ohi et al., 1994). More recently, it has been shown that over-expression of CDC5L in mammalian cells shortened the G2 phase of the cell cycle. Also, a dominant negative mutant of the protein lacking the carboxyl-terminal activation domain slowed G2 progression and delayed entry into mitosis (Bernstein and Coughlin, 1998).

[0004] The human protein PLRG1, recently identified as a component of the CDC5L complex, is highly homologous to the Arabidopsis thaliana PRL1 gene product. The PRL1 protein has been shown to be essential for the regulation of glucose and hormone responses in Arabidopsis thaliana (Nemeth et al., 1998). Mutations in PRL1 have pleiotropic phenotypes. For example, a prl1 mutation can cause transcriptional de-repression of glucose responsive genes; augment the sensitivity of the plants to growth hormones such as cytokinin, abscisic acid, ethylene and auxin; stimulate the accumulation of sugars and starch in the plants' leaves and inhibit root elongation (Nemeth et al., 1998). In both A. thaliana and COS-1 cells, PRL1 shows nuclear localisation and interacts with ATHKAP2, an α-importin nuclear import receptor (Nemeth et al., 1998). PLRG1 and the PRL1 protein both contain seven copies each of the phylogenetically conserved WD-repeat domains that were first characterised in beta transducin (Neer et al., 1994). Proteins with WD domains are thought to have regulatory functions in the cell as well as being involved in protein-protein interactions. These WD domain proteins have been identified in a variety of species, from human to the facultatively thermophilic actinomycete—Thermospora curvata (Janda et al., 1996; Smith et al., 1999). in a phenotypic screen for cell cycle mutants of an A. thaliana cDNA library in fission yeast, PRL1 was identified as one of 11 genes that can cause severe morphological changes in the yeast. This was interpreted to indicate that PRL1 may be involved in cell shape maintenance and/or regulation of the cell cycle (Xia et al., 1996). More recently, it has been shown that mutations in the PLRG1 homologue in Saccharomyces pombe: prp5⁺ result in defects in pre-mRNA splicing and also blocks progression of the cell division cycle at the G2/M phase (Potashkin et al., 1998).

[0005] As mentioned above, several recent studies have shown that CDC5L and PLRG1 are associated with pre-mRNA splicing factors (Neubauer et al., 1998; Tsai et al., 1999; McDonald et al., 1999; Burns et al., 1999; Ajuh et al., 2000). In yeast it has been demonstrated that cells lacking cdc5+ function are defective in pre-mRNA splicing (McDonald et al., 1999). The CDC5L gene product is highly conserved across species and homologues have been identified in several eukaryotic species including Saccharomyces pombe, Sacchammyces cerevisiae, C. elegans, D melanogaster and Xenopus laevis (Hiriyama and Shinozaki, 1996; Stukenberg et al., 1997; Ohi et al., 1998; Tsai et al, 1999). Like CDC5L, PLRG1 is also very highly conserved across species (Nemeth et al., 1998), suggesting essential cellular functions for these proteins. However, a direct role for PLRG1 in the catalytic steps of pre-mRNA splicing has not been shown in spite of its association with splicing factors.

[0006] A protein complex associated with CDC5L from HeLa nuclear extracts was recently purified and shown that this complex contains at least six “core” proteins (Ajuh et al., 2000). Two of the core proteins, which also are the most highly conserved across species, are CDC5L and PLRG1.

[0007] The present invention is based in part on the results of studies into the interaction of CDC5L and PRLG1 and the observation that CDC5L and PLRG1 interact directly in vitro.

[0008] It is amongst the objects of the present invention to provide a method of screening candidate agents for any modulatory effects on the binding of CDC5L to PLRG1.

[0009] It is also an object of the present invention to provide peptides capable of inhibiting pre-mRNA splicing.

SUMMARY OF THE INVENTION

[0010] In a first aspect the present invention provides a method for identifying a substance capable of modulating an interaction between (i) a CDC5L polypeptide or a homologue thereof, or a derivative thereof, and (ii) a PLRG1 polypeptide, or a homologue thereof, or a derivative thereof, which method comprises:

[0011] a) providing a CDC5L polypeptide or a homologue, or a derivative thereof, as a first component and a PLRG1 polypeptide or a homologue, or a derivative thereof, as a second component;

[0012] b) contacting the two components with a test substance under conditions that would permit the two components to interact in the absence of said test substance; and

[0013] c) determining whether said substance modulates the interaction between the first and second components.

[0014] The method may further comprise

[0015] d) administering a substance which has been determined to disrupt the interaction between the first and second components to a eukaryotic cell; and

[0016] e) determining the effect of the substance on the cell.

[0017] It is understood that the term “modulation” refers to both positive and negative modulation. “Positive modulation”, as used herein refers to an increase in the interaction such as binding of CDC5L polypeptide or a homologue thereof, or a derivative thereof to PLRG1 or a homologue thereof, or a derivative thereof relative to the level of binding and/or activity as a result of the binding in the absence of the substance. “Negative modulation” as used herein refers to a decrease in the interaction such as binding of CDC5L polypeptide or a homologue thereof, or a derivative thereof to PLRG1 or a homologue thereof, or a derivative thereof relative to the level of binding and/or activity as a result of the binding in the absence of the substance.

[0018] The invention further provides a substance capable of modulating an interaction between (i) a CDC5L polypeptide or a homologue thereof, or a derivative thereof, and (ii) PLRG1 or a homologue thereof, or a derivative thereof, for use in treating the human or animal body by therapy or for use in diagnosis, whether or not practised on the human or animal body. Such a substance may thus be used in the prevention or treatment of for example cancer, or fungal infections. Such a substance may be for example, a peptide fragment of CDC5L or PLRG1 designed to act competitively with the native CDC5L or PLRG1 and thereby prevent or reduce binding of CDC5L to PLRG1. This in turn is envisaged to prevent or reduce pre-mRNA splicing.

[0019] The invention therefore further provides a substance capable of modulating an interaction between (i) a CDC5L polypeptide, or a homologue thereof, or a derivative thereof, and (ii) PLRG1 or homologues thereof, or derivatives thereof, for use in regulating mRNA splicing and hence the cell cycle of a mammalian, yeast or fungal cell. The substance may be used for inhibiting protein synthesis by disrupting mRNA splicing and is therefore applicable to the treatment of diseases in which undesirable proliferation of cells or disease-causing agents occurs. In that event, the cell may for example be a tumour, yeast or fungal cell, or any other disease-causing organism which possesses or utilises CDC5L and PLRG1 or homologues, such as viruses, parasites and skin diseases, such as psoriasis.

[0020] The invention also provides a method of regulating and/or disrupting the cell cycle in a eukaryotic cell, which method comprises administering to said cell a substance capable of modulating an interaction between (i) a CDC5L polypeptide or a homologue thereof, or a derivative thereof, and (ii) PLRG1 or a homologue thereof, or a derivative thereof.

DETAILED DESCRIPTION OF THE INVENTION

[0021] Polypeptide Components

[0022] The first component comprises a CDC5L polypeptide or a homologue thereof or a derivative of CDC5L or of a CDC5L homologue. In particular, the inventors have identified a portion of the carboxy terminus region of CDC5L as being capable of interacting with PLRG1, specifically a region encompassing amino acid residues 602 to 800 of the human sequence (numbering according to that shown in FIG. 9a) and especially amino acid residues 706 to 800. It is postulated that the exact region responsible for the interaction with PLRG1 resides within residues 706 to 800, and therefore, may be smaller than this defined region. It is well within the skill of the person in the art to be able to identify the smaller regions by, for example, synthesising smaller regions comprising residues between 706 to 800 of CDC5L and examining their interaction with PLRG1AII amino acid residue numbers discussed herein are as shown in FIGS. 9(a) and 9(c) of the polypeptide sequences.

[0023] Therefore, the present invention provides a CDC5L polypeptide, homologue, fragment or derivative thereof. The fragments may be greater than 50, 60, 100 or 200 amino acid residues long. The minimum fragment length may be 80, 100 or 120 amino acid residues and may be 94 amino acid residues, which are capable of binding to PLRG1. Such fragments include fragments containing a portion of the carboxy terminal region of CDC5L, typically a region of CDC5L encompasssing amino acid residues 602 to 800, and preferably amino acid residues 706 to 800. It is thought that the exact region responsible for the interaction with PLRG1 resides within residues 706 to 800, while residues 602 to 706 appear to enhance the interaction between the polypeptides. Herein, substantial homology for fragments of CDC5L is regarded as a sequence which has at least 70%, eg. 80%, 90%, 95% or 98%, amino acid homology (identity) over at least 50, preferably 75, more preferably 100 amino acids with a portion of the carboxyl terminus of CDC5L.

[0024] Derivatives further include variants of CDC5L and its homologues or derivatives, including naturally occurring allelic variants and synthetic variants which are substantially homologous to said CDC5L and its homologues. The human CDC5L sequence may, for example, be found in the SwissProt database as accession number Q99974, and the yeast equivalent CeF1 sequence may, for example, be found in the SwissProt database as accession number NP_(—)013940.

[0025] The second component is selected from PLRG1 or homologues thereof, and their derivatives (derivatives are defined as for CDC5L). In addition to CDC5L, the present inventors have also identified a WD motif of PLRG1 which is capable of interacting with CDC5L, specifically amino acid residues 257 to 396. It is thought that the exact region responsible for the interaction with CDC5L resides within residues 257 to 396, and therefore, may be smaller than this defined region. It is also well within the skill of the person in the art to be able to identify the smaller regions, by, for example, synthesising smaller regions encompassed by residues 257 to 396 and examining their interaction with CDC5L.

[0026] The human PLRG1 sequence may, for example, be found in the Swiss Prot databasE as accession number O43660, and the S. pombe equivalent, PRP46, may for example, be found in the SwissProt database as accession number AAG01399, and the S. cerevisiae equivalent may, for example, be found in the SwissProt database as accession number NP_(—)015174.

[0027] Therefore, the present invention also provides a PLRG1 polypeptide or derivative thereof. Derivatives of PLRG1 include fragments, comprising at least 100, 140 or 160 amino acids, such as at least 130 amino acids, and for example 139 amino acids, which are capable of binding to CDC5L. Derivatives further include variants of PLRG1, its homologues or derivatives, for example, WD motifs found in other species, including naturally occurring allelic variants and synthetic variants which are substantially homologous to said PLRG1. In this context, substantial homology is regarded as a sequence which has at least 70%, eg. 80%, 90%, 95% or 98% amino acid homology (identity) over at least 80, such as 100, for example 140 amino acids with PLRG1. The WD motif (WD/40) is described in Neer et al (1994).

[0028] It will be understood that for the particular polypeptides embraced herein, natural variations such as may occur due to polymorphisms, can exist between individuals or between members of the family. These variations may be demonstrated by (an) amino acid difference (s) in the overall sequence or by deletions, substitutions, insertions, inversions or additions of (an) amino acid(s) in said sequence. All such derivatives showing the recognised modulatory activity are included within the scope of the invention. For example, for the purpose of the present invention conservative replacements may be made between amino acids within the following groups:

[0029] (I) Alanine, serine, threonine;

[0030] (II) Glutamic acid and aspartic acid;

[0031] (III) Arginine and leucine;

[0032] (IV) Asparagine and glutamine;

[0033] (V) Isoleucine, leucine and valine;

[0034] (VI) Phenylalanine, tyrosine and tryptophan.

[0035] Derivatives may be in the form of a fusion protein wherein CDC5L and/or PLRG1, a homologue or derivative thereof is fused, using standard cloning techniques, to another polypeptide which may, for example, comprise a DNA-binding domain, a transcriptional activation domain or a ligand suitable for affinity purification (for example glutathione-S-transferase or six consecutive histidine residues).

[0036] The first and second components used in the assays may be obtained from for example mammalian, yeast or fungal extracts, produced recombinantly from, for example, bacteria, yeast or higher eukaryotic cells including mammalian cell lines and insect cell lines, or synthesised de novo using commercially available synthesisers. Preferably, the first and second components used in the assays are recombinant.

[0037] Therefore, the present invention provides an assay system comprising CDC5L polypeptide, or derivatives thereof, and PLRG1 polypeptide, or derivatives thereof. Preferably, the assay comprises a derivative comprising a portion of the carboxy terminal region of CDC5L and a derivative comprising the WD motif region or fragment thereof PLRG1. More preferably, the assay comprises a derivative comprising a region encompassing amino acid residues 602 to 800, in particular amino acid residues 706 to 800, of CDC5L, and a derivative comprising amino acid residues 257 to 396 of PLRG1. The smaller regions are preferable due to their small size, resulting in potentially reduced complications in the production and handling of them.

[0038] Further, the present invention provides an isolated nucleic acid for the recombinant production of CDC5L, as disclosed in FIG. 10(a) or 10(b) or derivatives thereof, and an isolated nucleic acid for the recombinant production of PLRG1 as disclosed in FIG. 10(c), or derivatives thereof.

[0039] The invention still further provides a nucleotide sequence which is similar to the disclosed DNA sequences. By “similar” is meant a sequence which is capable of hybridising to a sequence which is complementary to the inventive nucleotide sequence. When the similar sequence and inventive sequence are double stranded the nucleic acid constituting the similar sequence preferably has a T_(m) within 20° C. of that of the inventive sequence.

[0040] In the case that the similar and inventive sequences are mixed together and denatured simultaneously, the Tm values of the sequences are preferably within 10° C. of each other. More preferably hybridization may be performed under stringent conditions, with either the similar or inventive DNA preferably being supported. Thus for example either a denatured similar or inventive sequence is preferably first bound to a support and hybridization may be effected for a specified period of time at a temperature of between 50 and 70° C. in double strength SSC (2×NaCl 17.5 g/l and sodium citrate (SC) at 8.8 g/l) buffered saline containing 0.1% sodium dodecyl sulphate (SDS) followed by rinsing of the support at the same temperature but with a buffer having a reduced SSC concentration. Depending upon the degree of stringency required, and thus the degree of similarity of the sequences, such reduced concentration buffers are typically single strength SSC containing 0.1% SDS, half strength SSC containing 0.1% SDS and one tenth strength SSC containing 0.1% SDS.

[0041] Sequences having the greatest degree of similarity are those the hybridization of which is least affected by washing in buffers of reduced concentration. It is most preferred that the similar and inventive sequences are so similar that the hybridization between them is substantially unaffected by washing or incubation at high stringency, for example, in one tenth strength sodium citrate buffer containing 0.1% SDS.

[0042] Candidate Substances

[0043] A substance which modulates an interaction between the first component and the second component may do so in several ways. It may directly modulate the binding of the two components by, for example, binding to one component and masking or altering the site of interaction with the other component. Candidate substances of this type may conveniently be screened by in vitro binding assays as, for example, described below. Examples of candidate substances include non-functional homologues of the first or second components as well as antibodies which recognise the first or second components.

[0044] Suitable candidate substances include for example peptides, especially of from about 10-15 to 100 amino acids in size, in particular 10 to 20 to 30 amino acids in size, based on the sequence of a region of CDC5L encompassing amino acid residues 706 to 800, or variants of such peptides in which one or more residues have been substituted, and peptides based on the sequence of a region of PLRG1 encompassing amino acid residues 257 to 396, or variants of such peptides in which one or more residues have been substituted.

[0045] It has been observed that the peptides NH₂-PEDTVDFLKEVESRMQHITQGRTSMKIQFK-COOH NH₂-PPTEVLLESIQSKVESIEQLQRKLQHVQ-COOH NH₂-EQQNNEMCSTLCHHSLPALIEG-COOH NH₂-HHSLPALIEGQRKYYADYYAYRQEI-COOH

[0046] Disrupt the interaction between CeF1 and PRP46 polypeptides (equivalent to human CDC5L and PLRG1, respectively) in yeast (S. cerevisiae).

[0047] Suitable candidate substances also include antibody products (for example, monoclonal and polyclonal antibodies, single chain antibodies, chimeric antibodies and CDR-grated antibodies) which are specific for the first component or the second component, preferably to residues 706 to 800 of CDC5L, or to residues 257 to 396 of PLRG1.

[0048] Furthermore, combinatorial libraries, peptide and peptide mimetics, defined chemical entities, oligonucleotides, and natural product libraries may be screened for activity as inhibitors of an interaction between the first component and the second component in assays such as those described below. The candidate substances may be used in an initial screen in batches of, for example 10 substances per reaction, and the substances of those batches which show inhibition tested individually. Candidate substances which show activity in in vitro screens such as those described below can then be tested in in vivo systems, such as mammalian, yeast or fungal cells which will be exposed to the inhibitor and tested for susceptibility to cell cycle disruption.

[0049] Assays

[0050] The assays of the invention may be in vitro assays or in vivo assays, for example using an animal, yeast or fungal model. One type of in vitro assay for identifying substances which disrupt an interaction between the first component and the second component involves:

[0051] contacting a first component, which is immobilised on a solid support, with a non-immobilised second component in the absence of a candidate substance;

[0052] contacting the first immobilised component with the non-immobilised second component in the presence of a candidate substance; and

[0053] determining if the candidate substance disrupts the interaction between the first component and the second component.

[0054] Alternatively, the second component may be immobilised and first component non-immobilised.

[0055] Binding of the first component to the second component (and vice-versa) may be determined by a variety of methods well-known in the art. For example, the non-immobilised component may be labelled (with for example, a radioactive label, an epitope tag or an enzyme-antibody conjugate). The effect of a candidate substance on an interaction between the two components can be determined by comparing the amount of label bound in the presence of the candidate substance with the amount of label bound in the absence of candidate substance. A lower amount of label bound in the presence of the candidate substance indicates that the candidate substance is an inhibitor of interactions between the first component and the second component.

[0056] Alternatively, binding may be determined by immunological detection techniques. For example, the reaction mixture can be Western blotted and the blot probed with an antibody that detects the non-immobilised component. ELISA techniques may also be used.

[0057] Candidate substances that are identifiable by the method of the invention as modulating an interaction between a first component and a second component may be tested for their ability to, for example, disrupt mRNA splicing, which may lead to inhibition of protein synthesis. Such compounds could be used therapeutically in regulating and/or disrupting the cell cycle of a mammalian, yeast or fungal cell, including, for example, inducing cell death in, for example, neoplastic cells, or preventing cell growth in yeast or fungal cells.

[0058] The present inventors have in fact identified peptides based on the human sequence of the CDC5L protein sequence between residues 706-740 and a corresponding region from other species (see FIG. 9a) which have been shown to inhibit pre-mRNA splicing.

[0059] More particularly the present inventors have found the region comprising the sequence EKKMKILLGGYQ (amino acid nos. 714-725) of the human sequence and corresponding sequences from other species to be able to inhibit pre-mRNA splicing. Additionally, each peptide appears to be generally species specific. That is, a peptide based on the corresponding region of for example Plasmodium falciparum has a significantly reduced effect on pre-mRNA splicing in human cells.

[0060] Thus, in a further aspect the present invention provides a peptide comprising the sequence EKKMKILLGGYQ of the human CDC5L polypeptide or corresponding region from a homologous sequence of a different species for use in inhibiting or reducing pre-mRNA splicing.

[0061] Corresponding regions from a homologous sequence of a different species may easily be determined by a skilled addressee and are shown for example in FIG. 9a. Suitable homologous sequences include EKKLKILTGGYZ from Drosophila melanogaster; EKKLGKVLGGYD from Lentinula (fungi); and ENKYDIYTKGYQ from Plasmodium falciparum.

[0062] As mentioned above, the present inventors have observed that the peptides are generally quite species specific. Thus, it is envisaged that the Lentinula peptide mentioned above could for example be used to treat fungal infections in humans, such that the peptide would inhibit fungal pre-mRNA splicing but not substantially effect human pre-mRNA splicing.

[0063] In addition to the CDC5L derived peptides described above which have been shown to disrupt pre-mRNA splicing, the present inventors have also identified peptides between positions 257-396 of the human PLRG1 sequence which can also inhibit pre-mRNA splicing. The following sequences have been shown to inhibit pre-mRNA splicing: PYLFSCCEDKQVKCWDLEYNKVIRHYHGHL and PQIITGSHDTTIRLWDLVAGKTRVTLTNHK.

[0064] Typically, an assay to determine the effect of a candidate substance identifiable by the method of the invention on the disruption of mRNA splicing in a mammalian, yeast or fungal cell comprises:

[0065] (a) administering the candidate substance to the cell; and

[0066] (b) determining the effect of the candidate substance on the cell cycle, including, for example the prevention of mRNA splicing which leads an inhibition of protein synthesis.

[0067] Administration of candidate substances to cells may be performed by for example adding directly to the cell culture medium or injection into the cell. The assay is typically carried out in vitro. The candidate substance is contacted with the cells, typically cells in culture. The cells may be cells of a mammalian, yeast or fungal cell line.

[0068] The ability of a candidate substance to reduce or prevent protein synthesis can be determined by administering a candidate compound to cells and determining if protein synthesis has been reduced in said cells. The effect of the disruption of protein synthesis can be measured indirectly by measuring the amount of spliced pre-mRNA in the cell after administration of the reagent or directly by measuring the incorporation of amino acids that have been radioactively, fluorescently labelled or any other tagged amino acids into newly synthesised proteins in cells exposed to the reagent. The tagged or labelled amino acids could be injected into cells or included in the growth medium after administration of the CDC5L reagent. Inhibition of protein synthesis is measured as the decrease in incorporation of labelled amino acids into proteins or by measuring the level of unspliced message i.e. accumulation of pre-mRNA due to splicing inhibition, or an absence of mature mRNA.

[0069] Therapeutic Uses

[0070] It has been demonstrated herein that mRNA splicing can be disrupted in HeLa cells. Whilst inhibition of splicing results in inhibition of de novo protein synthesis, protein already present in the cells remains intact. Not intending to be bound by theory, it is postulated that since new proteins, and hence protein synthesis, are required to complete a cell cycle in rapidly dividing cells, cells in which proliferation is undesirable, for example tumour cells, may be selectively targetted with agents which disrupt the interaction between CDC5L and PLRG1. It is thought that failure to complete the cell cycle in these cells may arrest tumour growth or even induce apoptosis.

[0071] Furthermore, although CDC5L and PLRG1 are also involved in mRNA splicing in yeast and fungal cells, it is postulated that differences between the human and yeast, and human and fungal proteins may be the target of agents which disrupt the interaction between CDC5L and PLRG1 (see FIG. 8). Hence, selecting for agents which disrupt only the yeast and fungal CDC5L and PLRG1 interaction may provide a selective treatment against these organisms.

[0072] Thus, the present invention provides a substance capable of modulating an interaction between (i) a CDC5L polypeptide or a homologue thereof, or a derivative thereof, and (ii) PLRG1 or homologues thereof, or derivatives thereof, for use in a method of disrupting mRNA splicing and hence substantially reducing protein synthesis. Typically, said substance may be used to target diseases in which cell proliferation is undesirable and may be used to induce cell death, for example in a tumour cell, or to prevent cell growth, in for example a tumour cell, a yeast or fungal cell(s).

[0073] The formulation of a substance according to the invention will depend upon the nature of the substance identified but typically a substance may be formulated for clinical use with a pharmaceutically acceptable carrier or diluent. For example it may be formulated for topical, parenteral, intravenous, intramuscular, subcutaneous, intraocular or transdermal administration. A physician will be able to determine the required route of administration for any particular patient and condition.

[0074] Typically, the substance is used in an injectable form. It may therefore be mixed with any vehicle which is pharmaceutically acceptable for an injectable formulation, preferably for a direct injection at the site to be treated. The pharmaceutically-acceptable carrier or diluent may be, for example, sterile or isotonic solutions. It is also preferred to formulate that substance in an orally active form.

[0075] The dose of substance used may be adjusted according to various parameters, especially according to the substance used, the age, weight and condition of the patient to be treated, the mode of administration used and the required clinical regimen. A physician will be able to determine the required route of administration and dosage for any particular patient and condition.

[0076] The present invention will now be further described by way of example and with reference to the Figures which show:

FIGURE LEGENDS

[0077]FIG. 1 illustrates that anti-CDC5L co-immunodepletes most of the PLRG1 from HeLa nuclear extract. Anti-CDC5L was used to immunodeplete CDC5L protein from nuclear extract. The beads containing immunoprecipitated proteins and supernatants from which CDC5L has been removed were loaded onto a 10% SDS-PAGE gel and probed by Western blotting using anti-CDC5L antibodies. Lanes marked 1 are the control lanes containing about 50 μg of HeLa nuclear extract and the lanes labelled 2 have the same amount of nuclear extract as lanes 1 except that the extract in lanes 2 was collected from an immunodepletion experiment using pre-immune IgG. The lanes marked 3 and 4 contained proteins eluted from protein G agarose beads used in the immunodepletion of CDC5L from nuclear extract by pre-immune IgG and anti-CDC5L antibodies respectively. The supernatant from the immunodepletion experiment using anti-CDC5L antibodies was loaded into the lanes labelled 5 of the figure. Immunoprecipitation reactions in panel A were probed with anti-CDC5L antibodies. Panels B and C contained identical samples as in A except that B and C were probed with anti-PLRG1 and anti-SPF30 antibodies respectively.

[0078]FIG. 2 illustrates that CDC5L co-localises with PLRG1 in vivo in human HeLa cells. HeLa cells were grown, transfected, and incubated with antibodies as described in the Materials and Methods section. The images shown in the panels are representative optical sections from the respective deconvolved data sets. All the panels marked (i) show antibody staining while the panels marked (ii) indicate the nuclear structures obtained using GFP-CDC5L or GFP-PLRG1. All the panels labeled (iii) show overlays of (i) and (ii) in each experiment.

[0079] (A) HeLa cells were transiently transfected with a plasmid expression vector encoding the GFP-PLRG1 fusion protein, fixed and stained with the anti-Sm protein monoclonal antibody Y12 (Petterson et al., 1984). Red represents Y12 staining and green indicates GFP-PLRG1 expression.

[0080] (B) A plasmid expression vector encoding GFP-CDC5L was used to transiently transfect HeLa cells that were subsequently fixed and stained with the same anti-Sm antibody as above. Red indicates Y12 staining as above while green here represents GFP-CDC5L expression.

[0081] (C) HeLa cells were transfected with the GFP-CDC5L plasmid expression vector as above. The cells were then fixed and stained with anti-PLRG1. Red represents anti-PLRG1 staining and green shows GFP-CDC5L expression. In all the panels, yellow indicates co-localisation of the two proteins CDC5L and PLRG1. Similar results were obtained using the protein specific antibodies instead of the GFP fusions (data not shown). Bar, 10 μm.

[0082]FIG. 3 illustrates the interaction between CDC5L and PLRG1 in vitro.

[0083] (A) GST-PLRG1 (lanes 2 and 3) was incubated for 20 minutes at room temperature with 0.5 mg of HeLa nuclear extract. An immunoprecipitation was performed on the reaction either using control pre-immune serum: CTRL1 (lane 2) or anti-CDC5L antibodies (lane 3). The blotted proteins from the immunprecipitates were probed with anti-PLRG1 antibodies. Lane 4 shows a pull-down experiment in which GST-CDC5L was incubated with nuclear extracts as above and the interacting proteins pulled down using 25-30 μl of glutathione sepharose beads. The blot was probed with anti-GST-PLRG1 antibodies. Lane 5 is a control reaction using GST alone in the pull-down experiment instead of GST-CDC5L. Lane 1 contained approximately 40 μg of HeLa nuclear extract. Note that the anti-GST-PLRG1 anti-serum (which also contains GST antibodies) recognises full-length GST-CDC5L and a minor band in lane 4 corresponding to a partial cleavage product of the GST-CDC5L protein used in the pull-down experiment as well as endogenous PLRG1.

[0084] (B) GST-PLRG1 (0.2 nmole) was used to pull down L-[³⁵S] methionine labeled in vitro translated CDC5L (5-8 μL). Lanes 1 and 2 are duplicate samples of the pull-down experiment whereas lanes 3 and 4 are controls using glutathione sepharose beads alone and GST respectively for pull-downs. Lane 5 contained about 30-40% of the input labeled CDC5L.

[0085] (C) GST-PLRG1 was used to pull down bacterially expressed His-tagged CDC5L. Lanes 1 and 2 contained duplicate samples of the pull-down of His-CDC5L by GST-PLRG1. Lane 3 had a control pull-down using the spliceosomal protein SPF30 which does not interact with CDC5L. Lane 4 is the positive control and contained His-CDC5L alone used in the binding assays. All the arrows on the right of the panels indicate proteins identified in the pull-down experiments.

[0086]FIG. 4 illustrates the identification of the PLRG1 binding domain in CDC5L.

[0087] (A) Point mutations were inserted into the CDC5L cDNA creating stop codons that resulted in truncation mutants when the protein is expressed. The arrows indicated the approximate length of expressed protein while the numbers to the right of the arrows show the position of the inserted stop codon. The letters a-f represent the different mutant proteins expressed.

[0088] (B) The CDC5L cDNAs with mutations were in vitro translated in the presence of L-[³⁵S] methionine and 3-4 μl of the expressed protein loaded onto a 12% SDS-PAGE gel. Protein bands were revealed by autoradiography. The lanes marked 1 to 6 represent the respective deletion mutants marked a to f. Lane 7 contained full-length CDC5L.

[0089] (C) Approximately 0.2 nmole of GST-PLRG1 was used in pull-down experiments with the deletion mutants a-f translated in vitro (8-10 μl). The lane marked G contained the control sample where GST was used to pull-down CDC5L instead of GST-PLRG1. Lanes 1-6 contained the mutant proteins a-f and lane 7 had a pull-down of CDC5L with GST-PLRG1.

[0090] (D) Overlapping carboxyl terminal sequences of the CDC5L cDNA were sub-cloned into the expression vector pET-30a (Novagen). The arrows indicate the cloned fragments and the numbers on the left and right-hand side of each arrow represent the start and end of each cDNA fragment. The letters g to j represent the respective sub-clones of the CDC5L cDNA.

[0091] (E) The sub-clones above were in vitro translated and 3-5 μL of the translated protein were run on a 12% SDS-PAGE gel. The protein bands were revealed by autoradiography. The lanes marked 2 to 5 contained the expressed proteins from the sub-clones g to j respectively. Lane 1 contained the full-length CDC5L protein.

[0092] (F) GST-PLRG1 was used to pull down the proteins from the clones g-j. Lane 1 is a positive control i.e. a pull-down of CDC5L using GST-PLRG1. Lanes 2-5 contained samples from pull-down experiments using GST-PLRG1 and the mutant proteins from g to j respectively.

[0093]FIG. 5 illustrates the identification of the CDC5L binding region in PLRG1.

[0094] (A) GST tagged PLRG1 cDNA was point mutated such that stop codons were inserted at specific sites. The arrows indicate the length of the reading frames after stop codon insertion. The numbers on the right of the arrows indicate the positions of the stop codons in the PLRG1 cDNA sequence. The letters a to c represent the cDNAs generated by the mutations.

[0095] (B) The GST-PLRG1 mutants were expressed in E. coli and the purified proteins used in pull-down assays with CDC5L. Lane 1 is a negative control pull-down using GST whereas lanes 2-4 are pull-downs using the proteins from a to c respectively. Lane 5 represents a positive control experiment where full-length GST-PLRG1 was used to pull-down CDC5L.

[0096] (C) Overlapping sequences containing the CDC5L binding region were sub-cloned into the pGEM-T vector (Promega) and pGEX-4-T1 (Pharmacia). The arrows indicate the cloned fragments and the numbers on the left and right-hand side of each arrow represent the start and end of each cDNA fragment. The letters d to f have been used to label the sub-clones produced.

[0097] (D) The cDNAs in pGEM-T were used for in vitro transcription/translation and the expressed protein bands revealed by autoradiography. The lanes marked 1-3 represent proteins expressed from the clones d to f respectively.

[0098] (E) The proteins expressed above were used in pull-down experiments with GST-CDC5L. Lane 1 is a control experiment in which GST alone was used to pull-down full-length L-[³⁵S] methionine-labelled PLRG1. The lanes marked 2-4 contained pull-downs using GST-CDC5L and the proteins expressed using the clones d to f.

[0099]FIG. 6 illustrates that the WD motif rich region of PLRG1 interacts with the carboxyl terminal of CDC5L.

[0100] (A) GST-ΔPLRG1f (PLRG1 mutant from clone f) was used to pull-down the carboxyl terminal truncated proteins of CDC5L i.e. ΔCDC5Lg and ΔCDC5Lh. Lane 1 is a control pull-down of CDC5L using GST alone. Lane 2 is a pull-down of CDC5L using full-length GST-PLRG1. Lanes 3 and 4 contained samples from experiments where GST-ΔPLRG1f was to pull down L-[³⁵S] methionine labelled ΔCDC5Lg and ΔCDC5Lh respectively.

[0101] (B) GST-ΔPLRG1f, ΔCDC5Lg and ΔCDC5Lj were expressed in E. coli and purified as described in the Materials and Methods section. GST-ΔPLRG1f was used to pull down ΔCDC5Lg or ΔCDC5Lj on to glutathione sepharose beads. All the reactions were carried out in duplicate. Lanes 1 and 2 contained reactions from a pull-down experiment using, ΔCDC5Lg and lanes 3 and 4 contained samples from a pull-down of hexahistidine ΔCDC5Lj using GST-ΔPLRG1f. Lanes 5 and 6 represent control pull-down experiments using GST and ΔCDC5Lg. Note that GST-ΔPLRG1f did not bind to the glutathione sepharose beads as efficiently as GST alone.

[0102] (C) Panel C is identical to B except that the nitrocellulose filter was probed with a protein-S alkaline phosphatase conjugate (Novagen).

[0103]FIG. 7 illustrates that the interaction between CDC5L and PLRG1 in nuclear extract is required for splicing catalysis.

[0104] (A) ΔCDC5Lh or ΔPLRG1f (approximately 1 nmole) was added to approximately 100 μg of HeLa nuclear extract followed by immunoprecipitation using about 15-20 μg rabbit anti-CDC5L antibodies. The immunoprecipitates were subsequently probed with sheep polyclonal anti-CDC5L and anti-PLRG1 antibodies. Lane 1 contained nuclear extract alone. The lanes marked 2, 3, 6 and 7 contained immunoprecipitates of anti-CDC5L except that ΔCDC5Lh alone was added to the nuclear extract in lane 3 and ΔPLRG1f was added to the extract in lane 6 while ΔCDC5Lh and GST-ΔPLRG1f were both added to the nuclear extract in lane 7. Lanes 4 and 5 contained negative control immunoprecipitation reactions using antibodies to HCF (a nuclear protein) and rabbit pre-immune IgG. The panels labelled i and ii were probed with anti-CDC5L and anti-PLRG1 antibodies respectively. The arrows on the right of the figure indicate the protein bands.

[0105] (B) Full-length and truncated proteins to be added to splicing reactions were expressed in E. coli and purified to the same extent by affinity chromatography. 2-10 μg of the purified proteins were run on a 4-12% gradient gel (Novex) and stained using colloidal coomassie stain according to the manufacturer's instructions. Lane 1 contained GST. Lanes 2 and 3 had ΔCDC5Lh and GST-ΔPLRG1f respectively. Lane 4 contained GST-PLRG1. The lane marked 5 contained SPF30 while lane 6 contained His-CDC5L. Minor bands in the gel represent degradation products of the expressed proteins.

[0106] (C) 0.05 to 0.2 nmoles of the bacterially expressed proteins were added to about 55 μg of HeLa nuclear extract and pre-incubated at room temperature for about 20 minutes before addition to pre-mRNA splicing reactions. The splicing reactions were incubated at 30° C. for about 90 minutes. Lane 1 contained the pre-mRNA used in the splicing experiments. Lanes 2 and 3 contained control splicing reactions except that 0.2 nmoles of GST were added to the reaction in lane 3. Lanes 4-6 represent splicing reactions to which increasing amounts of ΔCDC5Lh (0.05 to 0.2 nmoles) were added whereas the reactions in lanes 12-14 contained increasing amounts of GST-ΔPLRG1f. Lanes 7 and 8 contained splicing reactions to which were added increasing amounts (0.1 and 0.2 nmole respectively) of both ΔCDC5Lh and GST-ΔPLRG1f. The reactions in lanes 9, 10 and 11 contained the E. coli expressed proteins CDC5L, SPF30 and PLRG1 respectively.

[0107]FIG. 8 illustrates the inhibition of spliceosome assembly by ΔCDC5Lh The panels A-C represent native polyacrylamide/agarose gels used to separate spliceosome complexes. The bands on the gels were revealed by autoradiography. All the lanes marked CTRL1 contained control splicing reactions prepared and left on ice for 60 minutes. The lanes labelled CTRL2 are control reactions to which GST was added. Approximately 0.2 nmoles of bacterially expressed proteins were added to about 55 μg of HeLa nuclear extract and pre-incubated at room temperature for 20 minutes before addition to pre-mRNA splicing reactions as above except that the reactions here were incubated at 30° C. for 1 hour before loading on to native gels.

[0108] (A) Lane 1 contained a splicing reaction prepared and left on ice. Lane 2 is a control reaction to which was added GST. Lanes 3 and 4 contained reactions with had the ΔCDC5Lh and GST-ΔPLRG proteins added respectively. Lane 5 (CTRL3) contained a splicing reaction to which was added both ΔCDC5Lh and GST-ΔPLRG1f proteins. The two proteins had been pre-incubated together for 10 minutes at room temperature before addition into the splicing reactions.

[0109] (B) ΔCDC5Lh was added to splicing reactions at different time points. The time point—20 indicates that ΔCDC5Lh was pre-incubated with nuclear extract at room temperature for 20 minutes before the splicing reaction was started. The time points 0, 20, 40 and 60 correspond to the respective times in minutes at which ΔCDC5Lh was added to the splicing reactions after they had been started. All the reactions were allowed to run at 30° C. for up to 60 minutes after addition of the ΔCDC5Lh protein. Lanes 3-7 contain samples representing the different time points.

[0110] (C) A single splicing reaction was prepared and incubated for about 50 minutes after which the reaction was split into two aliquots. GST was added to the aliquot in lane 2 and ΔCDC5Lh was added to the aliquot in lane 3. The reactions were then allowed to continue for a further 10-15 minutes before stopping. Spliceosomal complexes were then separated on a native gel.

[0111]FIG. 9 illustrates amino acid alignments of (a) CDC5L from S. cerevisiae, S. pombe, A. thaliana, C. elegans, Drosophila and humans (b) the carboxyl terminal region of CDC5L from S. cerevisia, S. pombe, A. thaliana, C. elegans, Drosophila and humans, and (c) PLRG1 from yeast, A. thalian, C. elegans and humans. Residues shaded yellow differ from the consensus by 4 distance units, while residues shaded green match the consensus within 4 distance units.

[0112]FIG. 10 illustrates polynucleotides acid encoding (a) human CDC5L, (b) S. cerevisiae CEF 1 (equivalent to human CDC5L), (c) S. pombe CDC5+ (equivalent to human CDC5L), (d) human PLRG1, (e) S. cerevisiae Prp46p (equivalent to human PLRG1), and (f) S. pombe Prp5 (equivalent to human PLRG1).

[0113]FIG. 11 shows the splicing inhibition by a 24-mer CDC5L peptide from the PLRG1 interaction domain. Lane 1 in the figure contained the pre-mRNA used in the splicing experiment. Lane 2 is a positive control and no peptide was added to this reaction. The reaction in Lane 3 contained 20 nmole of a non-CDC5L peptide whereas the reactions in Lanes 4, 5 and 6 each contained 20 nmole of overlapping peptides (Nos. 1-3) designed from the PLRG1 interacting region of the CDC5L protein. The symbols on the right of the figure represent the pre-mRNA, splicing intermediates and products present in the reaction at the end of the experiment.

[0114]FIG. 12 shows the splicing inhibition by a 12-mer peptide designed from human peptide No. 1. The reaction in Lane 1 of this figure is the positive control containing no additional peptide. Lane 2 contained 20 nmole of the inhibitory 24-mer human CDC5L peptide no. 1. The splicing reactions in lanes 3-5 contained 20 nmole each of the 12-mer CDC5L peptides designed from the 24-mer inhibitory peptide. The symbols on the right of the figure represent the pre-mRNA, splicing intermediates and products present in the reaction at the end of the experiment.

[0115]FIG. 13 shows the species specific and dose dependent inhibition of pre-mRNA splicing by CDCL related peptides. Lane 1 in this figure contained the pre-mRNA used in the splicing experiment. The reaction in Lane 2 of this figure is the positive control containing no additional peptide. The splicing reactions in Lanes 3-8 contained 3, 6, 9, 12, 15 and 18 nmole of the inhibitory 12-mer human CDC5L peptide no. 5 respectively. Lane 9 contained the 12-mer reverse peptide ie. no. 8. The reactions in lanes 10 to 12 were performed in the presence of 20, 40 and 60 nmole respectively of the fungal (Lentinula) peptide ie. no 11. Splicing reactions in Lanes 13 to 15 were performed in the presence of 20, 40 and 60 nmole respectively of the Plasmodium falciparum peptide ie. no. 12. The symbols on the right of the figure represent the pre-mRNA, splicing intermediates and products present in the reaction at the end of the experiment.

[0116]FIG. 14 shows the affect of splicing inhibitors by PLRG1 derived peptide derived from the CDC5L binding domain. The sequences of the peptides used in the experiment are as follows:

[0117] PL1 sequence=PYLFSCGEDKQVKCWDLEYNKVIRHYHGHL

[0118] PL2 sequence=CSRDSTARIWDVRTKASVHTLSG

[0119] PL3 sequence=PQIITGSHDTTIRLWDLVAGKTRVTLTNHK

[0120] 7, 14 or 21 nmols of each peptide were added to each pre-mRNA splicing reaction.

EXAMPLES Materials and Methods

[0121] cDNA Cloning and Sequencing

[0122] The PLRG1 and CDC5L cDNAs were cloned from a HeLa cDNA library (Clontech) by PCR. Primers were designed for the amino and carboxyl termini of the proteins using previously deposited sequences for these cDNAs in the GeneBank database (PLRG1 accession no. AF044333 and CDC5L accession no. U86753). The PLRG1 primers contained BamHI and Xho I sites added to the 5′ ends of the 5′ and 3′-end primers respectively. The CDC5L PCR primers contained Sal I sites added to their 5′ ends. The PCR products were purified on a PCR purification column (Qiagen) according to the manufacturer's instructions. Purified PCR products were digested with the appropriate enzymes and cloned using standard methods into the compatible sites of the vectors pGEX-4T1 (Pharmacia), pET-30a (Novagen), pEGFP-C1 (Clontech) and pSG-9M a modified form of the plasmid pSG5 (Green et al., 1988) containing an amino terminus myc tag. The plasmid DNA was sequenced on the Applied Biosytems 377 automated DNA sequencer using the Taq dye terminator cycle sequencing method according to the manufacturer's instructions. pGEX-4T1 and pET-30a were used for expression of recombinant protein in E. coli while the pEGFP-C1 and pSG-9M vectors were used for expression in mammalian cells (HeLa). pET-30a clones were also used for in vitro transcription/translation experiments.

[0123] Expression of Recombinant Proteins in E. coli

[0124] cDNAs cloned into the pGEX-4T1 vector were used to transform E. coli BL21(DE3). Overnight cultures were grown from single colonies then diluted 1:10 in fresh LB medium with ampicillin (100 μg/ml) and grown at 30° C. to an OD₆₀₀ of 0.7-1.0 before induction with 0.1 mM IPTG. Three hours post induction, cells were pelleted and resuspended in 10 ml of PBS/0.5% Triton X-100 containing protease inhibitor cocktail (Boehringer). Cell lysis was achieved by sonication. The cell debris was removed by centrifugation at 10,000 g for 10 minutes. Preswollen glutathione-sepharose beads pre-equilibrated in PBS were added to the supernatant (1 ml per litre of culture). The beads were incubated with the crude protein extract for 2 hrs at 4° C. with rocking. Beads were collected and washed 3 times in PBS/0.5% Triton X-100 followed by 3 washes in PBS. Proteins were eluted from the beads by incubating in 25 mM glutathione in 50 mM Tris.Cl pH 8.0. The proteins were dialysed into a buffer containing 20 mM HEPES (pH8.0), 20% glycerol, 100 mM KCl, 0.2 mM EDTA, 1 mM dithiothreitol or PBS and stored at −80° C.

[0125] pET-30a cDNA clones were treated as above for expression except that 1 mM IPTG was used for induction and the cells were grown at 37° C. prior to induction at 30° C. The expressed protein was bound to Ni-NTA agarose beads (Qiagen) and the beads were washed with buffer containing 20 mM imidazole, 1 mM PMSF, 50 mM NaH₂PO₄, and 300 mM NaCl (pH 8.0). Recombinant protein was eluted from beads using the same buffer as above except that the concentration of imidazole was increased to 250 mM. Eluted proteins were dialysed in using the same buffer as above.

[0126] Antibody Production and Affinity Purification

[0127] Peptide antibodies to CDC5L and PLRG1 were prepared as described previously (Ajuh et al., 2000). Antibodies to bacterially expressed PLRG1 and CDC5L were also produced in sheep and rabbits (SAPU, Lanarkshire, Scotland, UK).

[0128] Splicing Assays

[0129] Nuclear extracts used in the splicing assays were obtained commercially from Computer Cell Culture Centre (Mons, Belgium). Splicing assays were done using uniformly labelled, capped pre-mRNAs incubated with nuclear extract as described previously (Lamond et al., 1997). In experiments where recombinant proteins were added to the splicing reactions, proteins that gave low yields during expression in E. coli and purification by affinity chromatography were concentrated using centrifugal filter devices (MWCO 3500) (Microcon) according to the manufacturer's instructions before addition to splicing reactions. The Adeno pre-mRNA was transcribed from Sau3AI digested plasmid pBSAd1 (Konarska and Sharp, 1987). The splicing reactions were loaded on a 10% polyacrylamide/8M urea denaturing gel and run in 1×TBE in order to separate the splicing products. When samples were to be used for the analysis of splicing complexes, the reactions were loaded onto a polyacrylamide/agarose composite gel (Konarska and Sharp, 1986) and run for about 5 hrs at 25 mA.

[0130] Immunoprecipitation of Proteins from HeLa Nuclear Extract

[0131] Immunoprecipitations of the spliceosomal proteins from nuclear extract were done using affinity purified peptide antibodies. 50 μl of nuclear extract (4-5 mg/ml) were pre-cleared for 1 hr at 4° C. on 25 μl of settled protein G or A sepharose (Pharmacia) or protein G/A agarose beads (Boehringer) that had been pre-incubated with 10 μg of sheep pre-immune IgG. The pre-cleared nuclear extract was diluted 10 times (except in immunodepletion experiments) with PBS buffer containing 0.5% Triton X-100 before adding to protein-G sepharose or agarose beads (25 μl) that had been pre-incubated with 30 pmoles of antibody for 1 hr at 4° C. Immunoprecipitations were carried out at 4° C. for 2-16 hrs. The immunoprecipitates were washed three times at 4° C. with 1 ml PBS containing 0.5% Triton X-100. Protein-G beads carrying the immune complexes were collected after each wash by centrifugation at 1500 g for 1 min. For immunodepletion experiments a higher amount of antibody (0.33 nmole/250 μg) of HeLa nuclear extract were used during the immunoprecipitation step.

[0132] SDS-PAGE and Western Blotting

[0133] SDS PAGE gel analysis was done as described previously (Laemmli, 1970). For immunoblotting, the washed immunoprecipitates were resuspended in 50 μl of 2×SDS PAGE loading buffer and heated at 95° C. for 5 mins. Approximately 10-15 μl of the supernatant were loaded on a 10% SDS PAGE gel or 4-12% pre-cast gradient gel (Novex). The separated proteins were transferred onto Hybond-C extra membrane (Amersham) by electroblotting. The membranes carrying the transferred proteins were blocked with 5% non-fat milk powder in PBS/0.3% Tween-20. The membranes were incubated with primary antibody for 1-16 hr at room temperature, washed with blocking buffer and incubated with the appropriate secondary antibody. The primary antibodies were used at the following dilutions: anti-CDC5L (1:1000); anti-PLRG1 (1:1000) and anti-SPF30 (dilution 1:2000). After washing the blots in blocking buffer 3-4 times (5 minutes per wash at room temperature), the membranes were then incubated with a secondary antibody to which has been covalently coupled horse radish peroxidase or alkaline phosphatase. Protein bands were detected by developing blots with the ECL kit (Amersham) according to the manufacturer's instructions or using NBT (60 μl of a 30 mg/ml solution)/BCIP (60 μl of a 25 mg/ml solution) in 10 ml of alkaline phosphatase buffer (0.1M NaHCO₃, 1 mM MgCl₂, pH 9.8) for colorimetric detection on the membrane.

[0134] In Vitro Transcription and Translation

[0135] The in vitro transcription and translation experiments were done with the T7 or SP6 RNA polymerase transcription/translation systems that used rabbit reticulocyte lysate (TNT systems, Promega) and L-[³⁵S] methionine (Amersham, AG1094) to produce [³⁵S] labelled proteins according to the manufacturer's recommendations. Aliquots of these reactions were used for protein-protein interaction assays as described below.

[0136] Protein Binding Assays

[0137] About 0.2 nmole of the appropriate GST-fusion recombinant protein was mixed with an equimolar amount of hexahistidine tagged bacterially expressed protein or 8-10 μl of the in vitro translation reaction above and incubated in binding buffer (250 mM NaCl, 50 mM HEPES pH 7:9, 2% BSA) at room temperature for 15 minutes. The binding reaction was then added to 25 μl of glutathione sepharose beads or antibody bound protein-G sepharose and mixed at 4° C. for 1-2 hrs. The beads were washed 3-4 times in 1 ml of PBS/0.1% Triton X-100 and resuspended in 25 μl 2×SDS PAGE loading dye before heating at 70° C. for 10 minutes or 95° C. for 5 minutes. Bound proteins were separated on a 10% or 12% SDS PAGE gel after which the gel was fixed in 50% methanol/10% acetic acid for 30 minutes. The fixed gel was then soaked in a fluorographic reagent (Amplify, Amersham) for 30 minutes before drying. Protein bands were detected by autoradiography at −80° C. after 4-16 hrs. For antibody probing, the gels containing proteins from the antibody beads were treated as described above in the SDS-PAGE and Western blotting section.

[0138] In Vitro Mutagenesis of the CDCL and PLRG1 cDNAs

[0139] Point mutations generating stop codons were inserted into the cDNAs at approximately 100 amino acids intervals by PCR using the QuikChange site directed mutagenesis kit (Stratagene) according to the manufacturer's instructions. The cDNAs were sequenced to confirm the presence of the appropriate mutations. Regions of the cDNAs involved in binding and overlapping regions were subcloned into the vectors pGEX-4T1 (Amersham-Pharmacia) or pET-30a (Novagen) for use in E. coli expression and protein-protein interaction assays.

[0140] Cell Culture and Transfection

[0141] HeLa cells were grown in Dulbecco's modified Eagles' medium supplemented with 10% foetal calf serum and 100 U/ml penicillin and streptomycin (Life Technologies Ltd). For immunofluorescence assays, cells were grown on coverslips and transfected using Effectene transfection reagent (Qiagen) according to the manufacturers instructions.

[0142] Cell Staining and Immunoflourescence Analyses

[0143] Cells were washed in PBS and fixed for 5 minutes in 3.7% (w/v) paraformaldehyde in CSK buffer (10 mM PIPES pH6.8; 10 mM NaCl; 300 mM sucrose; 3 mM MgCl₂; 2 mM EDTA) at room temperature. Permeabilisation was performed with 1% Triton X-100 in PBS for 15 minutes at room temperature. Cells were incubated with primary antibodies diluted in PBS with 1% goat serum for 35 mins to 1 hour, washed 3×10 minute with PBS, incubated for 35 mins to 1 hour with the appropriate secondary antibodies diluted in PBS with 1% goat serum and washed 3×10 minutes with PBS. Antibodies used were Y12 monoclonal antibody (anti-Sm) (Petterson et al., 1984) (dilution 1:500), rabbit anti-CDC5L (1:500) and rabbit anti-PLRG1. TRITC conjugated goat anti-mouse and Cy5 conjugated goat anti-rabbit secondary antibodies were also used (Jackson Immunochemicals). Microscopy and image analysis was carried out using a Zeiss DeltaVision Restoration microscope as described previously (Platani et al., 2000).

[0144] Peptide Synthesis

[0145] Peptides were synthesised by with N-terminal biotin by Eurogentec or Sigma-Genosys to >95% purity. Purified peptides were resuspended in water at concentrations of 2-10 mg/l and stored at −80° C.

[0146] The sequences of the designed peptides are shown in the table below. TABLE 1 Species Peptide Homo sapiens No. 1. HMTTEAKRAAKMEKKMKILLGGYQ No. 2. ELKKHEDSAIPRRLECLKEDVQRQ No. 3. EREKELQHRYADLLLEKETLKSKF No. 4. QYGGLLIKMKKEMKAARKAETTMH (reverse of 1) No. 5. EKKMKILLGGYQ No. 6. HMTTEAKRAAKM No. 7. KRAAKMEKKMKI No. 8 QYGGLLIKMKKE (reverse of 5) No. 9. KILLGGYQ Drosophila melanogaster No. 10. EKKLKILTGGYQ Lentinula (fungi) No. 11. EKKLGKVLGGYQ Plasmodium falciparum No. 12. ENKYDIYTKGYQ

[0147] Results

[0148] CDC5L and PLRG1 are co-immunodepleted from HeLa nuclear extract. The human CDC5L and PLRG1 proteins can be co-purified as part of a multi-protein complex that is essential for pre-mRNA splicing, as can their homologues in yeast (McDonald et al., 1999; Ajuh et al., 2000). It was also observed that CDC5L and PLRG1 are the most phylogenetically conserved proteins in the core CDC5L associated complex in HeLa nuclear extracts. These observations prompted the inventors to find out whether all the PLRG1 protein in HeCLa nuclear extract was co-immunoprecipitated upon immunodepletion of CDC5L. A GST-PLRG1 fusion protein was expressed in E. coli, purified and used to raise antibodies in sheep and rabbits for use in the analysis of the CDC5L-PLRG1 interaction. The immune serum obtained recognises the protein in HeLa nuclear extract as well as the bacterially expressed protein (FIG. 1B lane 1, FIG. 3A lane 3 and data not shown).

[0149] Anti-CDC5L antibodies (Ajuh et al., 2000) were used to immunodeplete CDC5L from HeLa nuclear extract and both the proteins bound on the beads and the proteins remaining in the supernatants separated by SDS PAGE and transferred onto a nitrocellulose membrane by Western blotting as described in the Materials and Methods section. Transferred proteins were probed using anti-CDC5L antibodies (FIG. 1A), anti-PLRG1 antibodies (FIG. 1B) and as a negative control, an antibody to the spliceosomal protein SPF30 (Neubauer et al., 1998), which was not identified in the human CDC5L complex (FIG. 1C). The results indicate that most of the PLRG1 is co-depleted upon immunodepletion of CDC5L from HeLa nuclear extract (FIGS. 1A and B, lanes 4 and 5). In contrast, the spliceosomal protein SPF30 remains in the supernatant i.e. is not associated with the CDC5L/PLRG1 complex. These data show that most of the PLRG1 in nuclear extract is stably associated with CDC5L.

[0150] CDC5L Co-Localises with PLRG1 In Vivo in HeLa Cell Nuclei.

[0151] Because of the tight association between CDC5L and PLRG1 found in immunoprecipitation experiments, it was next decided to study the association of these proteins in vivo. HeLa cells were either transfected with expression vectors encoding GFP-tagged CDC5L and PLRG1 proteins, or else stained with specific antibodies. PLRG1 and CDC5L both showed a speckled nuclear staining pattern, as judged by antibody staining and by expression of GFP-fusion proteins, which co-localised with the pattern obtained by co-staining the cells with the monoclonal antibody Y12 (FIGS. 2A and B). The antibody Y12 recognises the “Sm” proteins common to each of the major splicing snRNPs (Petterson et al., 1984). When HeLa cells transiently expressing GFP-CDC5L were stained with anti-PLRG1, both proteins were found to co-localise in the same speckled structures (FIG. 2C). Similar results were obtained by staining cells transiently expressing GFP-PLRG1 with anti-CDC5L antibodies (data not shown). These results are consistent with the presence of CDC5L and PLRG1 in a common complex in vivo, but do not address whether the proteins directly interact.

[0152] CDC5L and PLRG1 Interact Directly In Vitro

[0153] The present inventors then investigated a possible direct interaction between the two proteins using in vitro methods. HeLa nuclear extracts were incubated with GST-PLRG1 and an immunoprecipitation performed on the reaction mixture using anti-CDC5L antibodies. Immunoprecipitated proteins were then separated by SDS PAGE and blotted onto nitrocellulose filters before probing with anti-PLRG1 antibodies (FIG. 3A lane 3). The results show that bacterially expressed GST-PLRG1 as well as endogenous PLRG1 are co-immunoprecipitated by anti-CDC5L antibodies and thus GST-PLRG1 will associate with CDC5L in HeLa nuclear extract. To determine whether bacterially expressed CDC5L will interact with PLRG1 in nuclear extract, the bacterially expressed protein: GST-CDC5L was incubated with HeLa nuclear extract and bound protein selected using glutathione sepharose beads. After separation by SDS PAGE and transfer of proteins to nitrocellulose membranes as described above, the blots were probed with an antibody raised against GST-PLRG1 (FIG. 3A lane 4). These results indicate that GST-CDC5L expressed in E. coli will interact with PLRG1 in HeLa nuclear extract whereas GST alone does not (FIG. 3A compare lanes 4 and 5; the PLRG1 arrow on the right of the panel shows endogenous PLRG1 pulled down by GST-CDC5L).

[0154] It is possible that the CDC5L-PLRG1 interaction may be indirect because other protein factors in the nuclear extract may be involved in mediating the interaction e.g. acting as “bridging” factors. Therefore, in vitro translated CDC5L was used in a pull-down assay with E. coli expressed GST-PLRG1 fusion protein and glutathione agarose beads (see Materials and Methods section; FIG. 3B). The results indicate that the GST-PLRG1 fusion protein will pull down L-[³⁵S] methionine-labelled in vitro translated CDC5L (FIG. 3B, lanes 1 and 2), whereas neither glutathione sepharose beads nor GST alone will (FIG. 3B, lanes 3 and 4 respectively). In order to rule out any involvement of some component in the reticulocyte lysate used for in vitro translation mediating the binding, a GST pull-down was performed using only purified, bacterially expressed proteins, i.e. GST-PLRG1 and His-tagged CDC5L (FIG. 3C). The results show that GST-PLRG1 will bind CDC5L directly in vitro, whereas GST-SPF30 (Neubauer et al., 1998), another spliceosomal protein not found in the CDC5L complex, does not interact directly with CDC5L (FIG. 3C, compare lanes 1 and 2 with lane 3). Taken together, the above data indicate that PLRG1 and CDC5L directly interact with each other.

[0155] Identification of the PLRG1 Binding Domain in CDC5L

[0156] Having shown that CDC5L and PLRG1 will interact directly in vitro, we next decided to identify the protein domain in CDC5L needed for binding to PLRG1. Protein truncation mutants were prepared by inserting stop codons at approximately 100 amino acids intervals in the CDC5L sequence progressively from the amino terminus (FIG. 4A). The mutated CDC5L expression plasmids were then used for in vitro transcription/translation to produce L-[³⁵S] methionine-labelled truncated proteins lacking overlapping regions of the carboxyl terminus of the protein (FIG. 4B). The PLRG1 interaction domain in CDC5L was determined by using full-length GST-PLRG1 in pull-down experiments with each of the respective CDC5L truncation mutants. The full-length and the ΔCDC5Lf mutant proteins were efficiently pulled down (FIG. 4C lanes 6 and 7) and very little or none of the mutants a to e were pulled down (FIG. 4C lanes 1 to 5). These results indicate that truncated proteins lacking the carboxyl terminus of the protein, as well as GST, will not bind PLRG1. This means that the PLRG1 binding region in CDC5L is located towards the carboxyl end of the protein from about amino acid residue 600 to 800.

[0157] In order to determine the binding domain for PLRG1 in the CDC5L sequence, overlapping regions towards the 3′ end of the CDC5L cDNA were subcloned (FIG. 4D) and the protein fragments translated in vitro from these cDNA regions (FIG. 4E) were used with GST-PLRG1 in pull-down experiments (FIG. 4F). The results obtained show that full-length CDC5L and the mutant proteins translated in vitro from regions g (ΔCDC5Lg) and h (ΔCDC5Lh) were pulled down using full-length GST-PLRG1 (FIG. 4F lanes 1-3 respectively). The mutant proteins obtained from the regions i (ΔCDC5Li) and j (ΔCDC5Lj) did not bind to GST-PLRG1 (FIG. 4F lanes 4 and 5). The mutant protein ΔCDC5Lg was pulled down less efficiently compared to the ΔCDC5Lh protein and full-length CDC5L (compare lanes 1 and 3 with lane 2 of FIG. 4F). These experiments show that the carboxyl terminus sequence (amino acid residues 706 to 800) is essential for binding to PLRG1 whereas sequences upstream from amino acid 706 will not bind PLRG1. However, an enhancement in binding was consistently observed (compare FIG. 4F lanes 2 and 3) when the carboxyl terminal domain of CDC5L also contained the sequences upstream from amino acid position 706 (i.e. ΔCDC5Lh). Taken together, these data indicate that although the carboxyl terminal amino acids 706-800 (ΔCDC5Lg) are essential and sufficient for PLRG1 binding, upstream amino acids can either enhance, or stabilise, this interaction.

[0158] Identification of the CDC5L Binding Domain in PLRG1

[0159] Having identified the PLRG1 binding region in CDC5L, it was next decided to determine the CDC5L binding region in PLRG1. Protein truncation mutants were engineered by inserting stop codons at regular intervals of about 130 amino acids in a 5′-3′ direction in the PLRG1 cDNA sequence (FIG. 5A). The mutations were created in the GST-PLRG1 construct and the mutant proteins expressed in E. coli and purified. The expressed proteins were then used in GST pull-downs with L-[³⁵S] methionine-labelled full-length CDC5L (FIG. 5B). The pull-down experiments showed that full-length GST-PLRG1 (FIG. 5B lane 5) and the PLRG1 truncated protein that stops at amino acid position 390 (FIG. 5B lane 4) will bind to CDC5L whereas GST alone will not (FIG. 5B lane 1). The proteins terminating at positions 130 or 262 showed little or no binding (FIG. 5B, lanes 2 and 3). In order to determine a minimum binding sequence for CDC5L in PLRG1, we next prepared sub-clones of the PLRG1 cDNA containing overlapping sequences upstream and downstream from the amino acid positions 262-390 (FIG. 5C). The cDNA sub-clones were expressed and L-[³⁵S] methionine labelled in vitro by translation in reticulocyte lysate (FIG. 5D). The labelled proteins were then used in pull-down experiments with full-length GST-CDC5L. These experiments show that the overlapping fragments containing the amino acid sequence positions 257-396 will bind to CDC5L, whereas GST alone will not interact with L-[³⁵S] methionine labelled PLRG1 (FIG. 5E compare lane 1 with lanes 2-4).

[0160] In Vitro Analysis of the Interaction between the Carboxyl Terminus Region of CDC5L and the WD Domain of PLRG1

[0161] Because all the pull-down experiments described so far involved using either full-length CDC5L to pull down PLRG1 mutants, or full-length PLRG1 to pull down CDC5L mutants, it is possible that other regions in the full-length proteins, apart from those determined using our assays, might also play a role in the binding. In order to confirm that the interacting domains in CDC5L and PLRG1 that have been identified herein are alone sufficient for binding, the respective mutant proteins containing the identified minimal binding sequences were used in pull-down experiments (FIG. 6). In the first experiment GST-ΔPLRG1f (i.e. comprising amino acid positions 257-396) was used to pull-down in vitro translated, L-[³⁵S] methionine labelled ΔCDC5Lg and ΔCDC5Lh. The results indicate that the in vitro translated carboxyl terminal sequence of CDC5L comprising amino acids 602-800 and 706-800 (FIG. 6A lanes 3 and 4) will interact with the bacterially expressed PLRG1 mutant protein containing the amino acids from position 257-396 (GST-ΔPLRG1f).

[0162] It was then decided to study the interaction between ΔPLRG1f and ΔCDC5Lg using only bacterially expressed proteins in order to exclude the possibility that some component in the reticulocyte lysate used above in the in vitro translation experiments, may mediate the interaction between the two mutant proteins. GST-ΔPLRG1f and hexahistidine-tagged ΔCDC5Lg were expressed in E. coli and affinity purified using glutathione sepharose (Pharmacia) and nickel-agarose beads (Qiagen) respectively. The purified proteins were used in a GST pull-down assay (see Materials and Methods section). Bound proteins were separated by SDS PAGE and blotted onto nitrocellulose filters. The filters were stained using Blot FastStain, (Chemicon International) according to the manufacturer's instructions, to reveal all proteins pulled down by the glutathione sepharose beads (FIG. 6B). The results show that GST-ΔPLRG1f will pull-down His-tagged ΔCDC5Lg whereas GST does not (compare FIG. 6B lanes 1 and 2 with lanes 5 and 6). It was also observed that GST-ΔPLRG1f does not bind to the truncated protein ΔCDC5Lj that lacks the carboxyl terminus sequence of CDC5L (FIG. 6B lanes 3 and 4). Since the reagent used above to stain the blot (i.e. Blot FastStain) will stain any protein transferred onto the membrane, it implies that in order to rule out the possibility that the ΔCDC5Lg band may be a partial cleavage product of GST-ΔPLRG1f, the nitrocellulose membrane was stripped and then probed with protein-S alkaline phosphatase conjugate (Novagen) according to the manufacturer's instructions (FIG. 6C). ΔCDC5Lg used in these experiments was expressed in E. coli from the plasmid pET-30a (Novagen) that contains an S-tag which is downstream from the hexahistidine sequence and upstream from the ΔCDC5Lg sequence. Protein-S specifically binds to the S-tag that is present in proteins expressed from the pET-30a plasmid vector. The results obtained after probing the membrane with protein-S alkaline phosphatase confirm the observation above that GST-ΔPLRG1f pulls down His₆-ΔCDC5Lg (FIG. 6C lanes 1 and 2) whereas GST does not (FIG. 6C lanes 5 and 6). Taken together, these results show that the truncated proteins GST-ΔPLRG1f and ΔCDC5Lg will interact directly in vitro. This means that the protein sequences that have been tested are both necessary and sufficient for binding, while other amino acid sequences outside these regions in both proteins are not strictly required for binding to occur.

[0163] Disruption of the CDC5L-PLRG1 Interaction in HeLa Nuclear Extract Inhibits Pre-mRNA Splicing.

[0164] In order to characterise further the role of these highly conserved proteins, the present inventors next investigated the effect of adding the mutant proteins containing the interaction domains in both proteins on the CDC5L-PLRG1 complex in HeLa nuclear extract (FIG. 7). It was decided to use ΔCDC5Lh for most of the subsequent experiments because this mutant protein consistently showed a higher binding efficiency to PLRG1 than ΔCDC5Lg (FIG. 4 and data not shown). ΔCDC5Lh was added to HeLa nuclear extract and wild type CDC5L immunoprecipitated from the extract using a peptide anti-CDC5L antibody (Ajuh et al., 2000), whose recognition sequence is outside the sequence contained in ΔCDC5Lh. The immunoprecipitates were then probed with anti-CDC5L antibodies (FIG. 7Ai) and anti-PLRG1 antibodies, respectively (FIG. 7Aii). The data indicate that ΔCDC5Lh will disrupt the CDC5L/PLRG1 interaction in HeLa nuclear extract because it markedly reduces co-immunoprecipitation of PLRG1 by anti-CDC5L antibodies (FIG. 7Aii lane 3). However, when the CDC5L mutant is pre-incubated with ΔPLRG1f, the disruption of the CDC5L/PLRG1 complex in HeLa nuclear extract is blocked (FIG. 7Aii lane 7). This is presumably due to the titration of the ΔCDC5Lh interaction domain by ΔPLRG1f. It was observed that although the PLRG1 mutant protein will bind to ΔCDC5Lh, it was not as efficient as ΔCDC5Lh in disrupting the CDC5L/PLRG1 interaction in HeLa nuclear extract (compare FIG. 7Aii lanes 3 and 6). The reason for this is not clear. It is possible that although ΔPLRG1f alone is sufficient for binding to CDC5L in vitro, another region of PLRG1 may be required to stabilise this interaction in HeLa nuclear extract. The absence of such a region in ΔPLRG1f may reduce the mutant protein's ability to compete with wild-type PLRG1 in nuclear extract for binding to CDC5L.

[0165] The present inventors next investigated the effect on pre-mRNA splicing of the disruption of the CDC5L-PLRG1 interaction in HeLa nuclear extract by the mutant proteins. The mutant proteins, as well as full-length proteins, were expressed in E. coli and purified as described in the Materials and Methods section. Under the expression conditions, some of the proteins gave high yields e.g. ΔCDC5Lh and PLRG1 (FIG. 7B lanes 2 and 4), while others, such as the ΔPLRG1f and CDC5L gave relatively lower yields (FIG. 7B lanes 3 and 6). When ΔCDC5Lh was added to splicing reactions, both the catalytic steps of pre-mRNA splicing were inhibited (FIG. 7C lanes 4-6) whereas splicing was unaffected upon addition of GST, GST or hexahistidine-tagged CDC5L or SPF30 (FIG. 7C lanes 3, 9 and 10 and data not shown). Addition of ΔPLRG1f alone (FIG. 7C lanes 12 to 14) inhibited splicing, although not as efficiently as ΔCDC5Lh, consistent with the previous observation of its inefficient disruption of the CDC5L/PLRG1 interaction in HeLa nuclear extract (FIG. 7A). On the other hand, when equimolar amounts of ΔCDC5Lh and ΔPLRG1f were pre-incubated together before addition to the splicing reaction, the splicing inhibition was much reduced compared to when ΔCDC5Lh is added alone (FIG. 7C, compare lanes 5 and 6 with lanes 7 and 8). This means that the interaction between the two mutant proteins has reduced their ability to disrupt the CDC5L/PLRG1 complex in the HeLa nuclear extract, thus allowing splicing to progress. The addition of full-length PLRG1 to the splicing reactions did not inhibit pre-mRNA splicing (FIG. 7C lane 11). Taken together, these results show that the interaction between CDC5L and PLRG1 in HeLa nuclear extract is important for the extract's ability to splice adeno pre-mRNA.

[0166] Effect of the Addition of ΔCDC5Lh and ΔPLRG1f Proteins to HeLa Nuclear Extract on Spliceosome Assembly.

[0167] It had been previously found that removal of CDC5L from HeLa nuclear extract by immunoprecipitation will inhibit pre-mRNA splicing, with the second catalytic step being more sensitive whereas spliceosome assembly on the pre-mRNA is not prevented (Ajuh et al., 2000). It was therefore decided to investigate whether spliceosome assembly is affected by the disruption of the CDC5L/PLRG1 interaction in HeLa nuclear extract (FIG. 8A). When ΔCDC5Lh was added to nuclear extract and the extract pre-incubated with the mutant proteins before addition to a splicing reaction, spliceosome assembly was inhibited and neither the pre-spliceosome nor spliceosome complexes were formed (FIG. 8A lane 3). The CDC5Lh mutant was found to be more efficient in this inhibition than the PLRG1f protein which showed little or no inhibition (FIG. 8A compare lanes 3 and 4). However, when equimolar amounts of the ΔPLRG1f and ΔCDC5Lh mutants were pre-incubated before addition to the nuclear extract the inhibitory effect of ΔCDC5Lh was blocked (FIG. 8A lane 5). This implies that the interaction between ΔPLRG1f and ΔCDC5Lh has prevented ΔCDC5Lh from interfering with the CDC5L-PLRG1 complex in the nuclear extract.

[0168] The present inventors next attempted to determine the step at which ΔCDC5Lh inhibits spliceosome assembly. Splicing reactions were set up as described in the Materials and Methods section and ΔCDC5Lh was added to these reactions at different time points. After the addition of ΔCDC5Lh, the reactions were allowed to proceed up to one hour. The reactions were then loaded on to native polyacrylamide/agarose composite gels and run for several hours. Bands corresponding to splicing complexes were revealed by autoradiography. The results obtained indicate that when ΔCDC5Lh was added to the nuclear extract and either pre-incubated for 20 minutes, or added immediately prior to commencement of the reaction, (time points −20 and 0 respectively, FIG. 8B lanes 3 and 4) the formation of spliceosome complexes was blocked. At the other time points i.e. adding ΔCDC5Lh between 20 and 60 minutes, progressively more spliceosomal complexes are detected assembled on the pre-mRNA (FIG. 8B lanes 5-7). These results indicate that the addition of ΔCDC5Lh inhibits any further assembly of spliceosomes after its addition to the reactions. It is also possible that the presence of the mutant protein disrupts some forms of assembled complexes.

[0169] In order to determine whether ΔCDC5Lh was disrupting assembled splicing complexes or inhibiting the formation of new complexes after its addition, a splicing reaction was set up under standard conditions and then allowed to run for about 50 minutes. The reaction was then split into two aliquots: GST was added to one aliquot i.e. the control, and to the other, an equimolar amount of ΔCDC5Lh was added. Both aliquots were then incubated for a further 10 minutes at 30° C. before being stopped. Splicing complexes formed were separated on a native gel and bands corresponding to these complexes were revealed by autoradiography (FIG. 8C). The results obtained show that ΔCDC5Lh will not disrupt spliceosomal complexes after they have been formed (FIG. 8C lane 3). Although ΔCDC5Lh was found to be unable to disrupt the spliceosome complexes, it is possible that its presence in the reaction may make the assembled complexes less stable.

[0170] Heparin is routinely added to splicing reactions at low concentrations before separation on native gels because it enhances the migration of the complexes into the gel leaving relatively less material stuck in the wells. However, heparin also has the property of disrupting aggregates and large protein complexes. It was next decided to investigate if the presence of ΔCDC5Lh caused pre-assembled spliceosome complexes on the pre-mRNA to be more sensitive to heparin treatment. Pre-mRNA splicing reactions were set up as described above and in duplicate tubes. After allowing the reactions to run for 50 minutes, GST or ΔCDC5Lh were added to separate duplicate tubes and the reaction allowed to proceed for a further 10-15 minutes. Heparin was then added to each of the reactions and the reactions incubated for 5 minutes at room temperature before loading on to native polyacrylamide/agarose gels as mentioned above. The results obtained from this experiment showed that the presence of ΔCDC5Lh does not make the spliceosomal complexes formed more sensitive to heparin treatment (data not shown). Taken together, these results indicate that ΔCDC5Lh will inhibit the formation of any new complexes after its addition to a splicing reaction and that the inhibition of spliceosome assembly occurs at an early step, perhaps prior to or, concomitant with the formation of the commitment complex

[0171] Discussion

[0172] The present inventors have recently shown that the human proteins CDC5L and PLRG1 are members of a non-snRNA containing multi-protein complex that is essential for pre-mRNA splicing in HeLa nuclear extracts (Ajuh et al., 2000). In yeast, the CDC5L homologue has also been found to be in a complex with the yeast homologue of PLRG1 (McDonald et al., 1999). However, a direct interaction between these two proteins has not previously been reported, nor has the functional significance of the association of these two highly conserved proteins in sub-spliceosomal complexes been demonstrated. Their high degree of sequence conservation across species suggests that both proteins may perform essential biological roles in the cell.

[0173] In this study it has been shown that CDC5L and PLRG1 are associated with each other in vivo and in HeLa nuclear extract. It has also been shown that CDC5L interacts directly with PLRG1 in vitro. The regions that mediate the direct interactions between the two proteins in vitro have been mapped to the carboxyl terminal domain of CDC5L and the WD40 motif region of PLRG1. By using the CDC5L mutant protein containing the PLRG1 binding domain, it has also been shown that the CDC5L/PLRG1 interaction in nuclear extract can be disrupted and that this disruption can lead to the inhibition of spliceosome assembly and pre-mRNA splicing catalysis in vitro. Taken together, the observations herein indicate that the direct interaction between the highly conserved proteins, CDC5L and PLRG1 in nuclear extract is essential for pre-mRNA splicing.

[0174] The results in this study indicate that the presence of a disrupted CDC5L complex in HeLa nuclear extract caused by the mutant protein ΔCDC5Lh interferes with the assembly of spliceosomes. This is presumably a dominant negative effect of the disrupted complex because its presence is not strictly required for assembly. This possibility is supported by the observations that the mutant protein ΔPLRG1f, which is not efficient in disrupting the CDC5L-PLRG1 interaction in HeLa nuclear extracts, does not prevent spliceosome assembly. Secondly, the fact that ΔCDC5Lh blocks formation of splicing complexes once added to a reaction but does not disrupt complexes that have already been formed, further supports the view that the presence of a disrupted CDC5L complex may interfere with the de novo assembly of spliceosomal complexes. Therefore, while the present inventors cannot rigorously exclude the possibility that the previous observations that immunodepletion of CDC5L from HeLa nuclear extract inhibits catalysis but not spliceosome assembly (Ajuh et al., 2000) may be due to incomplete removal of the interacting proteins with the low level of remaining proteins sufficient to promote spliceosome assembly and, to a lesser extent, the first catalytic step of splicing, the alternative explanation is favoured. Namely that the disrupted components of the CDC5L complex inhibit spliceosome formation, although the complex is not strictly required for assembly to proceed.

[0175] Although the CDC5L and PLRG1 proteins and their homologues have previously been identified in spliceosomal protein complexes (Neubauer et al., 1998; Tsai et al., 1999; McDonald et al., 1999; Ajuh et al, 2000) their possible direct interactions with other splicing factors have not yet been investigated in detail. Interestingly, in yeast, the CDC5L homologue CEF1 has been shown to interact with the splicing factor Prp19p through a region in the carboxyl terminal half of the protein and this region has also been shown to be essential for CEF1 self-interaction (Tsai et al., 1999). Saccharomyces cerevisiae Prp19p is required for the first catalytic step of splicing and may associate with the spliceosome either after, or simultaneously, with U4 snRNP dissociation from the complex. It has therefore been suggested that Prp19p may play a role in mediating the structural rearrangements in the spliceosome during U4 dissociation (Tam et al., 1993; Chen et al., 1998). The human homologue of yeast Prp19 has not yet been characterised, although we have identified a Prp19-like protein in our recent study of the CDC5L complex in HeLa nuclear extract (Ajuh et al., 2000). It is thus possible that both Prp19 and PLRG1 may interact, either simultaneously, or alternatively, with the carboxyl terminal domain of CDC5L. The length of the Prp19 binding domain identified in the yeast CEF1 protein is about 30 amino acids. The equivalent sequence to the above region in humans, determined by comparative sequence analysis, is about 100 amino acids upstream from the 94 amino acid region we have identified as the PLRG1 binding sequence in CDC5L. The involvement of the WD motif domain of PLRG1 in binding to CDC5L is consistent with the suggestion that proteins containing these regions may have a role in multiple simultaneous or consecutive protein-protein interactions (Smith et al., 1999). Although PLRG1 has not previously been shown to interact directly with specific pre-mRNA splicing factors, there is some evidence that this protein may interact with other cellular proteins not directly involved in splicing, such as protein kinase C-βII and α-importin ATHKAP2 (Nemeth et al., 1998).

[0176] In yeast, the CDC5L homologue CEF1 has been shown to mediate the targeting of the CDC5L associated complex to the spliceosome as a single multi-protein complex (Tsai et al., 1999). These findings are consistent with the observations that ΔPLRG1f on its own did not significantly inhibit spliceosome assembly, whereas ΔCDC5Lh was more efficient in inhibiting assembly. This may be because the CDC5L mutant protein containing the PLRG1 binding domain may not only disrupt the CDC5L/PLRG1 complex in nuclear extract but also interfere with interactions between other splicing factors that need to be targeted to the assembling spliceosome. Secondly, because the carboxyl terminal region has been shown to be needed for self-interaction in the S. cerevisiae homologue of CDC5L (CEF1) (Tsai et al., 1999), it is possible that our CDC5L mutant inhibits CDC5L self-interactions. These self-interactions may be essential for the function of the protein in pre-mRNA splicing. Further studies on characterising the direct protein-protein interactions between core members of the CDC5L, associated complex should shed more light on how these interactions affect the pre-mRNA splicing mechanism.

[0177] CDC5L and its homologues in other species have already been implicated in several cellular roles in addition to pre-mRNA splicing; for example, cell cycle progression (Nasmyth and Nurse, 1981; Ohi et al., 1994; Bernstein and Coughlin, 1998), sequence specific double stranded DNA binding and transcription activation in HeLa cells. The transcription activation ability of the protein was determined by using a vector containing a luciferase reporter fused downstream from a CDC5L binding site. It was observed that luciferase activity is increased by about 28 fold when the HeLa cells were co-transfected with a plasmid expressing CDC5L (Lei et al., 2000). It is thus possible that CDC5L may be needed in the cell for pre-mRNA splicing, transcription and cell division. Like CDC5L, the PLRG1 homologue in Arabidopsis thaliana called PRL1 has been shown to have a pleiotropic role in several regulatory pathways in this species. These include glucose metabolism, hormonal responses, transcription of genes regulated by sucrose and cytokinin, and regulation of SNF1-like kinases (Nemeth et al., 1998; Bhalerao et al., 1999). Thus, the CDC5L and PLRG1 proteins in eukaryotes may be directly involved in several cellular functions as mentioned above. Alternatively, it may be that some of the above observations are an indirect consequence of changes in the expression of specific genes in these organisms mediated by the role of CDC5L and PLRG1 in the mechanism of pre-mRNA splicing. Further studies are now required to characterise in more detail the interaction of the CDC5L/PLRG1 complex with other splicing factors in order to understand the contribution of such interactions to the splicing reaction.

[0178] Use of Peptides Derived from the Binding Regions of CDC5L; and PLRG1 in Inhibiting Pre-mRNA Splicing

[0179] A 24-Mer Peptide from the CDC5L Region that Binds PLRG1 Will Inhibit Splicing

[0180] 24 mer peptides were designed as shown in table 1 for Homo sapiens (Nos. 1-3) and 16 nmol of purified peptides were added to 30 μL splicing reactions (FIG. 11). Splicing intermediates were then separated on a denaturing gel as described in the Materials and Methods section. The results obtained indicate that the human peptide No. 1 will inhibit splicing (FIG. 11 Lane 3) whereas a non-specific peptide or the other human peptides (Lanes 5 and 6) did not inhibit splicing, Down the right hand side of the Figure and FIGS. 12, 13 and 14 there is a schematic representation of products observed on the gels. The starting product (a) consists of exon 1 and exon 2 together with intervening intro, this is the pre-mRNA substrate. In step 1 the free 5′ exon 1 intermediate (b) and the lariat intro and exon 2 intermediate (c) are generated. Further splicing produces the spliced exons 1 and 2 (d) and the excised lariat product (e). This is further explained in detail in Biochimca et Biophysica Acta (1993) 1173, 247-265 (G. M. Lamm and A. I. Lamond).

[0181] A 12 Mer Peptide Designed from Human Peptide No. 1 Will Also Inhibit Splicing

[0182] Overlapping peptide sequences were designed from human peptide sequence No. 1 (ie. numbers 5-7). The peptides were synthesised and purified by Sigma-Genosys to >95% purity. The purified peptides were added to splicing reactions as above. The results obtained show that peptides number 1 and 5 will inhibit splicing (FIG. 12, Lanes 2 and 3) whereas the other peptides do no. Peptide number 8 (the reverse sequence to peptide No. 5) was used as a control.

[0183] Species Specific and Dose Dependent Inhibition of Pre-mRNA Splicing by CDCL Related Peptides

[0184] Splicing assays were set up as described above using the peptides number 5, 10, 11 and 12. Peptides were added to the splicing reactions in amounts ranging from 3 to 60 nmole (FIG. 13). The results from this experiment indicate that 15-20 nmole of the human peptide will inhibit splicing whereas splicing inhibition only starts at 60 nmole when using the fungal peptide (FIG. 13, Lane 12). The Plasmodium peptide starts inhibiting at about 40 nmole (FIG. 13, Lane 14) and completely inhibits splicing at 60 nmole (FIG. 13, Lane 15). The reverse peptides were not able to inhibit splicing (FIG. 13, Lane 14 and data not shown). The Drosophila peptide did not inhibit splicing at 20 nmole. However, higher concentrations of this peptide have not yet been tested. Based on the above date, our prediction is that this peptide would also inhibit splicing when used at levels over 20-60 nmole.

[0185] Inhibition of Pre-mRNA Splicing by PLRG1 Derived Peptides

[0186] Splicing assays were set up as described above using peptides PL1, PL2 and PL3. Peptides were added to the splicing reactions ranging from 7 to 21 nmoles (FIG. 14). As can be seen PL1 and PL3 have the ability to inhibit pre-mRNA splicing.

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1 43 1 30 PRT Saccharomyces cerevisiae 1 Pro Glu Asp Thr Val Asp Phe Leu Lys Glu Val Glu Ser Arg Met Gln 1 5 10 15 His Ile Thr Gln Gly Arg Thr Ser Met Lys Ile Gln Phe Lys 20 25 30 2 28 PRT Saccharomyces cerevisiae 2 Pro Pro Thr Glu Val Leu Leu Glu Ser Ile Gln Ser Lys Val Glu Ser 1 5 10 15 Ile Glu Gln Leu Gln Arg Lys Leu Gln His Val Gln 20 25 3 22 PRT Saccharomyces cerevisiae 3 Glu Gln Gln Asn Asn Glu Met Cys Ser Thr Leu Cys His His Ser Leu 1 5 10 15 Pro Ala Leu Ile Glu Gly 20 4 25 PRT Saccharomyces cerevisiae 4 His His Ser Leu Pro Ala Leu Ile Glu Gly Gln Arg Lys Tyr Tyr Ala 1 5 10 15 Asp Tyr Tyr Ala Tyr Arg Gln Glu Ile 20 25 5 12 PRT Homo sapiens 5 Glu Lys Lys Met Lys Ile Leu Leu Gly Gly Tyr Gln 1 5 10 6 12 PRT Drosophila melanogaster 6 Glu Lys Lys Leu Lys Ile Leu Thr Gly Gly Tyr Glx 1 5 10 7 12 PRT Lentinula (Fungi) 7 Glu Lys Lys Leu Gly Lys Val Leu Gly Gly Tyr Asp 1 5 10 8 12 PRT Plasmodium sp. 8 Glu Asn Lys Tyr Asp Ile Tyr Thr Lys Gly Tyr Gln 1 5 10 9 30 PRT Homo sapiens 9 Pro Tyr Leu Phe Ser Cys Cys Glu Asp Lys Gln Val Lys Cys Trp Asp 1 5 10 15 Leu Glu Tyr Asn Lys Val Ile Arg His Tyr His Gly His Leu 20 25 30 10 30 PRT Homo sapiens 10 Pro Gln Ile Ile Thr Gly Ser His Asp Thr Thr Ile Arg Leu Trp Asp 1 5 10 15 Leu Val Ala Gly Lys Thr Arg Val Thr Leu Thr Asn His Lys 20 25 30 11 24 PRT Homo sapiens 11 His Met Thr Thr Glu Ala Lys Arg Ala Ala Lys Met Glu Lys Lys Met 1 5 10 15 Lys Ile Leu Leu Gly Gly Tyr Gln 20 12 24 PRT Homo sapiens 12 Glu Leu Lys Lys His Glu Asp Ser Ala Ile Pro Arg Arg Leu Glu Cys 1 5 10 15 Leu Lys Glu Asp Val Gln Arg Gln 20 13 24 PRT Homo sapiens 13 Glu Arg Glu Lys Glu Leu Gln His Arg Tyr Ala Asp Leu Leu Leu Glu 1 5 10 15 Lys Glu Thr Leu Lys Ser Lys Phe 20 14 24 PRT Homo sapiens 14 Gln Tyr Gly Gly Leu Leu Ile Lys Met Lys Lys Glu Met Lys Ala Ala 1 5 10 15 Arg Lys Ala Glu Thr Thr Met His 20 15 12 PRT Homo sapiens 15 His Met Thr Thr Glu Ala Lys Arg Ala Ala Lys Met 1 5 10 16 12 PRT Homo sapiens 16 Lys Arg Ala Ala Lys Met Glu Lys Lys Met Lys Ile 1 5 10 17 12 PRT Homo sapiens 17 Gln Tyr Gly Gly Leu Leu Ile Lys Met Lys Lys Glu 1 5 10 18 8 PRT Homo sapiens 18 Lys Ile Leu Leu Gly Gly Tyr Gln 1 5 19 12 PRT Drosophila melanogaster 19 Glu Lys Lys Leu Lys Ile Leu Thr Gly Gly Tyr Gln 1 5 10 20 12 PRT Lentinula (Fungi) 20 Glu Lys Lys Leu Gly Lys Val Leu Gly Gly Tyr Gln 1 5 10 21 590 PRT Saccharomyces cerevisiae 21 Met Pro Pro Val Pro Ile Tyr Val Lys Gly Gly Val Trp Thr Asn Val 1 5 10 15 Glu Asp Gln Ile Leu Lys Ala Ala Val Gln Lys Tyr Gly Thr His Gln 20 25 30 Trp Ser Lys Val Ala Ser Leu Leu Gln Lys Lys Thr Ala Arg Gln Ser 35 40 45 Glu Leu Arg Trp Asn Glu Tyr Leu Asn Pro Lys Leu Asn Phe Thr Glu 50 55 60 Phe Ser Lys Glu Glu Asp Ala Gln Leu Leu Asp Leu Ala Arg Glu Leu 65 70 75 80 Pro Asn Gln Trp Arg Thr Ile Ala Asp Met Met Ala Arg Pro Ala Gln 85 90 95 Val Cys Val Glu Arg Tyr Asn Arg Leu Leu Glu Ser Glu Asp Ser Gly 100 105 110 Gly Ala Ala Leu Ser Thr Gly Val Thr Asp Leu Lys Ala Gly Asp Ile 115 120 125 Asn Pro Asn Ala Glu Thr Gln Met Ala Arg Pro Asp Asn Gly Asp Leu 130 135 140 Glu Asp Glu Glu Lys Glu Met Leu Ala Glu Ala Arg Ala Arg Leu Leu 145 150 155 160 Asn Thr Gln Gly Lys Lys Ala Thr Arg Lys Ile Arg Glu Arg Met Leu 165 170 175 Glu Glu Ser Lys Arg Ile Ala Glu Leu Gln Lys Arg Arg Glu Leu Lys 180 185 190 Gln Ala Gly Ile Asn Val Ala Ile Lys Lys Pro Lys Lys Lys Tyr Gly 195 200 205 Thr Asp Ile Asp Tyr Asn Glu Asp Ile Val Tyr Glu Gln Ala Pro Met 210 215 220 Pro Gly Ile Tyr Asp Thr Ser Thr Glu Asp Arg Gln Ile Lys Lys Lys 225 230 235 240 Phe Glu Gln Phe Glu Arg Lys Val Asn Arg Lys Gly Leu Asp Gly Asn 245 250 255 Lys Asp Lys Pro Ser Lys Lys Asn Lys Asp Lys Lys Arg Lys His Asp 260 265 270 Glu Asn Glu His Val Glu Lys Ala Ala Leu Gly Glu Ser Thr Thr Leu 275 280 285 Thr Asp Glu Tyr Lys Lys Pro Lys Leu Ile Leu Ser Ala Pro Gly Thr 290 295 300 Lys Gln Gly Lys Val Thr Tyr Lys Lys Lys Leu Glu Ser Lys Arg Gln 305 310 315 320 Lys Leu Ile Glu Ala Gln Ala Thr Gly Thr Val Leu Thr Pro Lys Glu 325 330 335 Leu Leu Pro His Asp Ser Gly Gln Glu Asp Asn Glu Arg Ser Asn Ile 340 345 350 Lys Ser Gly Lys Gln Leu Lys Ser Arg Ile Arg Lys Phe Leu Val Gln 355 360 365 Met Phe Ala Ser Leu Pro Ser Pro Lys Asn Asp Phe Glu Ile Val Leu 370 375 380 Ser Glu Asp Glu Lys Glu Glu Asp Ala Glu Ile Ala Glu Tyr Glu Lys 385 390 395 400 Glu Phe Glu Asn Glu Arg Ala Met Asn Glu Glu Asp Asn Phe Ile Glu 405 410 415 Pro Pro Ser Gln Asn Asp Ala Pro Arg Val Ser Leu Val Ala Val Pro 420 425 430 Leu Ala Tyr Ser Thr Leu Pro Ile Pro Glu Phe Lys Asn Asn Pro Gln 435 440 445 Ser Ala Ile Asp Asn Lys Tyr Asn Leu Leu Val Ala Asn Ala Ile Asn 450 455 460 Lys Glu Pro His Met Val Pro Glu Asp Thr Val Asp Phe Leu Lys Glu 465 470 475 480 Val Glu Ser Arg Met Gln His Ile Thr Gln Gly Arg Thr Ser Met Lys 485 490 495 Ile Gln Phe Lys Thr Ala Met Pro Pro Thr Glu Val Leu Leu Glu Ser 500 505 510 Ile Gln Ser Lys Val Glu Ser Ile Glu Gln Leu Gln Arg Lys Leu Gln 515 520 525 His Val Gln Pro Leu Glu Gln Gln Asn Asn Glu Met Cys Ser Thr Leu 530 535 540 Cys His His Ser Leu Pro Ala Leu Ile Glu Gly Gln Arg Lys Tyr Tyr 545 550 555 560 Ala Asp Tyr Tyr Ala Tyr Arg Gln Glu Ile Arg Ser Leu Glu Gly Arg 565 570 575 Arg Lys Arg Leu Gln Ala Met Leu Asn Ser Ser Ser Ser Ile 580 585 590 22 757 PRT Schizosaccharomyces pombe 22 Met Val Val Leu Lys Gly Gly Ala Trp Lys Asn Thr Glu Asp Glu Ile 1 5 10 15 Leu Lys Ala Ala Val Ser Lys Tyr Gly Lys Asn Gln Trp Ala Arg Ile 20 25 30 Ser Ser Leu Leu Val Arg Lys Thr Pro Lys Gln Cys Lys Ala Arg Trp 35 40 45 Tyr Glu Trp Ile Asp Pro Ser Ile Lys Lys Thr Glu Trp Ser Arg Glu 50 55 60 Glu Asp Glu Lys Leu Leu His Leu Ala Lys Leu Leu Pro Thr Gln Trp 65 70 75 80 Arg Thr Ile Ala Pro Ile Val Gly Arg Thr Ala Thr Gln Cys Leu Glu 85 90 95 Arg Tyr Gln Lys Leu Leu Asp Asp Leu Glu Ala Lys Glu Asn Glu Gln 100 105 110 Leu Gly Leu Ile Ser Gly Glu Gly Ala Glu Ala Ala Ala Pro Val Asn 115 120 125 Asp Pro Asn Ser Arg Leu Arg Phe Gly Glu Ala Glu Pro Asn Leu Glu 130 135 140 Thr Leu Pro Ala Leu Pro Asp Ala Ile Asp Met Asp Glu Asp Glu Lys 145 150 155 160 Glu Met Leu Ser Glu Ala Arg Ala Arg Leu Ala Asn Thr Gln Gly Lys 165 170 175 Lys Ala Lys Arg Lys Asp Arg Glu Lys Gln Leu Glu Leu Thr Arg Arg 180 185 190 Leu Ser His Leu Gln Lys Arg Arg Glu Leu Lys Ala Ala Gly Ile Asn 195 200 205 Ile Lys Leu Phe Arg Arg Lys Lys Asn Glu Met Asp Tyr Asn Ala Ser 210 215 220 Ile Pro Phe Glu Lys Lys Pro Ala Ile Gly Phe Tyr Asp Thr Ser Glu 225 230 235 240 Glu Asp Arg Gln Asn Phe Arg Glu Lys Arg Glu Ala Asp Gln Lys Ile 245 250 255 Ile Glu Asn Gly Ile Arg Asn Asn Glu Met Glu Ser Glu Gly Arg Lys 260 265 270 Phe Gly His Phe Glu Lys Pro Lys Pro Ile Asp Arg Val Lys Lys Pro 275 280 285 Asn Lys Asp Ala Gln Glu Glu Lys Met Arg Arg Leu Ala Glu Ala Glu 290 295 300 Gln Met Ser Lys Arg Arg Lys Leu Asn Leu Pro Ser Pro Thr Val Ser 305 310 315 320 Gln Asp Glu Leu Asp Lys Val Val Lys Leu Gly Phe Ala Gly Asp Arg 325 330 335 Ala Arg Ala Met Thr Asp Thr Thr Pro Asp Ala Asn Tyr Ser Thr Asn 340 345 350 Leu Leu Gly Lys Tyr Thr Gln Ile Glu Arg Ala Thr Pro Leu Arg Thr 355 360 365 Pro Ile Ser Gly Glu Leu Glu Gly Arg Glu Asp Ser Val Thr Ile Glu 370 375 380 Val Arg Asn Gln Leu Met Arg Asn Arg Glu Gln Ser Ser Leu Leu Gly 385 390 395 400 Gln Glu Ser Ile Pro Leu Gln Pro Gly Gly Thr Gly Tyr Thr Gly Val 405 410 415 Thr Pro Ser His Ala Ala Asn Gly Ser Ala Leu Ala Ala Pro Gln Ala 420 425 430 Thr Pro Phe Arg Thr Pro Arg Asp Thr Phe Ser Ile Asn Ala Ala Ala 435 440 445 Glu Arg Ala Gly Arg Leu Ala Ser Glu Arg Glu Asn Lys Ile Arg Leu 450 455 460 Lys Ala Leu Arg Glu Leu Leu Ala Lys Leu Pro Lys Pro Lys Asn Asp 465 470 475 480 Tyr Glu Leu Met Glu Pro Arg Phe Ala Asp Glu Thr Asp Val Glu Ala 485 490 495 Thr Val Gly Val Leu Glu Glu Asp Ala Thr Asp Arg Glu Arg Arg Ile 500 505 510 Gln Glu Arg Ile Ala Glu Lys Glu Arg Leu Ala Lys Ala Arg Arg Ser 515 520 525 Gln Val Ile Gln Arg Asp Leu Ile Arg Pro Ser Val Thr Gln Pro Glu 530 535 540 Lys Trp Lys Arg Ser Leu Glu Asn Glu Asp Pro Thr Ala Asn Val Leu 545 550 555 560 Leu Lys Glu Met Ile Ala Leu Ile Ser Ser Asp Ala Ile Asn Tyr Pro 565 570 575 Phe Gly Asn Ser Lys Val Lys Gly Thr Ala Asn Lys Val Pro Asp Leu 580 585 590 Ser Asn Glu Glu Ile Glu Arg Cys Arg Leu Leu Leu Lys Lys Glu Ile 595 600 605 Gly Gln Leu Glu Ser Asp Asp Tyr Ile Gln Phe Glu Lys Glu Phe Leu 610 615 620 Glu Thr Tyr Ser Ala Leu His Asn Thr Ser Ser Leu Leu Pro Gly Leu 625 630 635 640 Val Ile Tyr Glu Glu Asp Asp Glu Asp Val Glu Ala Ala Glu Lys Phe 645 650 655 Tyr Thr Asn Asp Ile Gln Arg Asp Leu Ala Lys Lys Ala Leu Glu Cys 660 665 670 Asn Lys Leu Glu Asn Arg Val Tyr Asp Leu Val Arg Ser Ser Tyr Glu 675 680 685 Gln Arg Asn Phe Leu Ile Lys Lys Ile Ser His Ala Trp Lys Ala Leu 690 695 700 Gln Thr Glu Arg Lys Asn Leu Thr Cys Tyr Glu Phe Leu Tyr Asn Gln 705 710 715 720 Glu Arg Leu Ala Leu Pro Asn Arg Leu Glu Ala Ala Glu Ile Glu Leu 725 730 735 Ser Lys Met Gln Gln Ile Glu Ala Tyr Ala Gln Gln Asp Tyr Ala Arg 740 745 750 Val Thr Gly Gln Asn 755 23 844 PRT Arabidopsis thaliana 23 Met Arg Ile Met Ile Lys Gly Gly Val Trp Lys Asn Thr Glu Asp Glu 1 5 10 15 Ile Leu Lys Ala Ala Val Met Lys Tyr Gly Lys Asn Gln Trp Ala Arg 20 25 30 Ile Ser Ser Leu Leu Val Arg Lys Ser Ala Lys Gln Cys Lys Ala Arg 35 40 45 Trp Tyr Glu Trp Leu Asp Pro Ser Ile Lys Lys Thr Glu Trp Thr Arg 50 55 60 Glu Glu Asp Glu Lys Leu Leu His Leu Ala Lys Leu Leu Pro Thr Gln 65 70 75 80 Trp Arg Thr Ile Ala Pro Ile Val Gly Arg Thr Pro Ser Gln Cys Leu 85 90 95 Glu Arg Tyr Glu Lys Leu Leu Asp Ala Ala Cys Thr Lys Asp Glu Asn 100 105 110 Tyr Asp Ala Ala Asp Asp Pro Arg Lys Leu Arg Pro Gly Glu Ile Asp 115 120 125 Pro Asn Pro Glu Ala Lys Pro Ala Arg Pro Asp Pro Val Asp Met Asp 130 135 140 Glu Asp Glu Lys Glu Met Leu Ser Glu Ala Arg Ala Arg Leu Ala Asn 145 150 155 160 Thr Arg Gly Lys Lys Ala Lys Arg Lys Ala Arg Glu Lys Gln Leu Glu 165 170 175 Glu Ala Arg Arg Leu Ala Ser Leu Gln Lys Arg Arg Glu Leu Lys Ala 180 185 190 Ala Gly Ile Asp Gly Arg His Arg Lys Arg Lys Arg Lys Gly Ile Asp 195 200 205 Tyr Asn Ala Glu Ile Pro Phe Glu Lys Arg Ala Pro Ala Gly Phe Tyr 210 215 220 Asp Thr Ala Asp Glu Asp Arg Pro Ala Asp Gln Val Lys Phe Pro Thr 225 230 235 240 Thr Ile Glu Glu Leu Glu Gly Lys Arg Arg Ala Asp Val Glu Ala His 245 250 255 Leu Arg Lys Gln Asp Val Ala Arg Asn Lys Ile Ala Gln Arg Gln Asp 260 265 270 Ala Pro Ala Ala Ile Leu Gln Ala Asn Lys Leu Asn Asp Pro Glu Val 275 280 285 Val Arg Lys Arg Ser Lys Leu Met Leu Pro Pro Pro Gln Ile Ser Asp 290 295 300 His Glu Leu Glu Glu Ile Ala Lys Met Gly Tyr Ala Ser Asp Leu Leu 305 310 315 320 Ala Glu Asn Glu Glu Leu Thr Glu Gly Ser Ala Ala Thr Arg Ala Leu 325 330 335 Leu Ala Asn Tyr Ser Gln Thr Pro Arg Gln Gly Met Thr Pro Met Arg 340 345 350 Thr Pro Gln Arg Thr Pro Ala Gly Lys Gly Asp Ala Ile Met Met Glu 355 360 365 Ala Glu Asn Leu Ala Arg Leu Arg Asp Ser Gln Thr Pro Leu Leu Gly 370 375 380 Gly Glu Asn Pro Glu Leu His Pro Ser Asp Phe Thr Gly Val Thr Pro 385 390 395 400 Arg Lys Lys Glu Ile Gln Thr Pro Asn Pro Met Leu Thr Pro Ser Met 405 410 415 Thr Pro Gly Gly Ala Gly Leu Thr Pro Arg Ile Gly Leu Thr Pro Ser 420 425 430 Arg Asp Gly Ser Ser Phe Ser Met Thr Pro Lys Gly Thr Pro Phe Arg 435 440 445 Asp Glu Leu His Ile Asn Glu Asp Met Asp Met Gln Gln Ser Ala Lys 450 455 460 Leu Glu Arg Gln Arg Arg Glu Glu Ala Arg Arg Ser Leu Arg Ser Gly 465 470 475 480 Leu Thr Gly Leu Pro Gln Pro Lys Asn Glu Tyr Gln Ile Val Ala Gln 485 490 495 Pro Pro Pro Glu Glu Ser Glu Glu Pro Glu Glu Lys Ile Glu Glu Asp 500 505 510 Met Ser Asp Arg Ile Ala Arg Glu Lys Ala Glu Glu Glu Ala Arg Gln 515 520 525 Gln Ala Leu Leu Lys Lys Arg Ser Lys Val Leu Gln Arg Asp Leu Pro 530 535 540 Arg Pro Pro Ala Ala Ser Leu Ala Val Ile Arg Asn Ser Leu Leu Ser 545 550 555 560 Ala Asp Gly Asp Lys Ser Ser Val Val Pro Pro Thr Pro Ile Glu Val 565 570 575 Ala Asp Lys Met Val Arg Glu Glu Leu Leu Gln Leu Leu Glu His Asp 580 585 590 Asn Ala Lys Tyr Pro Leu Asp Asp Lys Ala Glu Lys Lys Lys Gly Ala 595 600 605 Lys Asn Arg Thr Asn Arg Ser Ala Ser Gln Val Leu Ala Ile Asp Asp 610 615 620 Phe Asp Glu Asn Glu Leu Gln Glu Ala Asp Lys Met Ile Lys Glu Glu 625 630 635 640 Gly Lys Phe Leu Cys Val Ser Met Gly His Glu Asn Lys Thr Leu Asp 645 650 655 Asp Phe Val Glu Ala His Asn Thr Cys Val Asn Asp Leu Met Tyr Phe 660 665 670 Pro Thr Arg Ser Ala Tyr Glu Leu Ser Ser Val Ala Gly Asn Ala Asp 675 680 685 Lys Val Ala Ala Phe Gln Glu Glu Met Glu Asn Val Arg Lys Lys Met 690 695 700 Glu Glu Asp Glu Lys Lys Ala Glu His Met Lys Ala Lys Tyr Lys Thr 705 710 715 720 Tyr Thr Lys Gly His Glu Arg Arg Ala Glu Thr Val Trp Thr Gln Ile 725 730 735 Glu Ala Thr Leu Lys Gln Ala Glu Ile Gly Gly Thr Glu Val Glu Cys 740 745 750 Phe Lys Ala Leu Lys Arg Gln Glu Glu Met Ala Ala Ser Phe Arg Lys 755 760 765 Lys Asn Leu Gln Glu Glu Val Ile Lys Gln Lys Glu Thr Glu Ser Lys 770 775 780 Leu Gln Thr Arg Tyr Gly Asn Met Leu Ala Met Val Glu Lys Ala Glu 785 790 795 800 Glu Ile Met Val Gly Phe Arg Ala Gln Ala Leu Lys Lys Gln Glu Asp 805 810 815 Val Glu Asp Ser His Lys Leu Lys Glu Ala Lys Leu Ala Thr Gly Glu 820 825 830 Glu Glu Asp Ile Ala Ile Ala Met Glu Ala Ser Ala 835 840 24 755 PRT Caenorhabditis elegans 24 Met Val Arg Val Ile Ile Lys Gly Gly Val Trp Lys Asn Thr Glu Asp 1 5 10 15 Glu Ile Leu Lys Ala Ala Ile Met Lys Tyr Gly Lys Asn Gln Trp Ser 20 25 30 Arg Ile Ala Ser Leu Leu His Arg Lys Ser Ala Lys Gln Cys Lys Ala 35 40 45 Arg Trp Phe Glu Trp Leu Asp Pro Gly Ile Lys Lys Thr Glu Trp Ser 50 55 60 Arg Glu Glu Asp Glu Lys Leu Leu His Leu Ala Lys Leu Met Pro Thr 65 70 75 80 Gln Trp Arg Thr Ile Ala Pro Ile Val Gly Arg Thr Ser Ala Gln Cys 85 90 95 Leu Glu Arg Tyr Glu His Leu Leu Asp Glu Ala Gln Arg Lys Ala Glu 100 105 110 Gly Leu Asp Glu Glu Ala Thr Glu Thr Arg Lys Leu Lys Pro Gly Glu 115 120 125 Ile Asp Pro Thr Pro Glu Thr Lys Pro Ala Arg Pro Asp Pro Ile Asp 130 135 140 Met Asp Asp Asp Glu Leu Glu Met Leu Ser Glu Ala Arg Ala Arg Leu 145 150 155 160 Ala Asn Thr Gln Gly Lys Lys Ala Lys Arg Lys Ala Arg Glu Arg Gln 165 170 175 Leu Ser Asp Ala Arg Arg Leu Ala Ser Leu Gln Lys Arg Arg Glu Met 180 185 190 Arg Ala Ala Gly Leu Ala Phe Ala Arg Lys Phe Lys Pro Lys Arg Asn 195 200 205 Gln Ile Asp Tyr Ser Glu Glu Ile Pro Phe Glu Lys His Val Pro Ala 210 215 220 Gly Phe His Asn Pro Ser Glu Asp Arg Tyr Val Val Glu Asp Ala Asn 225 230 235 240 Gln Lys Ala Ile Glu Asp His Gln Lys Pro Arg Gly Arg Glu Ile Glu 245 250 255 Met Glu Met Arg Arg Glu Asp Arg Glu Lys Leu Lys Lys Arg Lys Glu 260 265 270 Gln Gly Glu Ala Asp Ala Val Phe Asn Ile Lys Glu Lys Lys Arg Ser 275 280 285 Lys Leu Val Leu Pro Glu Pro Gln Ile Ser Asp Arg Glu Leu Glu Gln 290 295 300 Ile Val Lys Ile Gly His Ala Ser Asp Ser Val Arg Gln Tyr Ile Asp 305 310 315 320 Gly Thr Ala Thr Ser Gly Leu Leu Thr Asp Tyr Thr Glu Ser Ala Arg 325 330 335 Ala Asn Ala Val Ala Ala Arg Thr Met Arg Thr Pro Met Leu Lys Asp 340 345 350 Thr Val Gln Leu Glu Leu Glu Asn Leu Met Ala Leu Gln Asn Thr Glu 355 360 365 Ser Ala Leu Lys Gly Gly Leu Asn Thr Pro Leu His Glu Ser Glu Leu 370 375 380 Gly Lys Gly Val Leu Pro Thr Pro Lys Val Ala Ala Thr Pro Asn Thr 385 390 395 400 Val Leu His Ala Ile Ala Ala Thr Pro Gly Thr Gln Ser Gln Phe Pro 405 410 415 Gly Ser Thr Pro Gly Gly Phe Ala Thr Pro Ala Gly Ser Val Ala Ala 420 425 430 Thr Pro Phe Arg Asp Gln Met Arg Ile Asn Glu Glu Ile Ala Gly Ser 435 440 445 Ala Leu Glu Gln Lys Ala Ser Leu Lys Arg Ala Leu Ala Ser Leu Pro 450 455 460 Thr Pro Lys Asn Asp Phe Glu Val Val Gly Pro Asp Asp Asp Glu Val 465 470 475 480 Glu Gly Ala Val Glu Asp Glu Ser Asn Gln Asp Glu Asp Gly Trp Ile 485 490 495 Glu Asp Ala Ser Glu Arg Ala Glu Asn Lys Ala Lys Arg Asn Ala Glu 500 505 510 Asn Arg Val Arg Asn Met Lys Met Arg Ser Gln Val Ile Gln Arg Ser 515 520 525 Leu Pro Lys Pro Thr Lys Val Asn Glu Gln Ala Thr Arg Ala Thr Asn 530 535 540 Ser Ser Ala Asp Asp Met Val Lys Ala Glu Met Ser Lys Leu Leu Ala 545 550 555 560 Trp Asp Val Asp Asn Lys Pro Pro Ser Val Ile Tyr Ser Arg Glu Glu 565 570 575 Leu Asp Ala Ala Ala Asp Leu Ile Lys Gln Glu Ala Glu Ser Gly Pro 580 585 590 Glu Leu Asn Ser Leu Met Trp Lys Val Val Glu Gln Cys Thr Ser Glu 595 600 605 Ile Ile Leu Ser Lys Asp Lys Phe Thr Arg Ile Ala Ile Leu Pro Arg 610 615 620 Glu Glu Gln Met Lys Ala Leu Asn Asp Glu Phe Gln Met Tyr Arg Gly 625 630 635 640 Trp Met Asn Gln Arg Ala Lys Arg Ala Ala Lys Val Glu Lys Lys Leu 645 650 655 Arg Val Lys Leu Gly Gly Tyr Gln Ala Ile His Asp Lys Leu Cys Lys 660 665 670 Lys Tyr Gln Glu Val Thr Thr Glu Ile Glu Met Ala Asn Ile Glu Lys 675 680 685 Lys Thr Phe Glu Arg Leu Gly Glu His Glu Leu Lys Ala Ile Asn Lys 690 695 700 Arg Val Gly Arg Leu Gln Gln Glu Val Thr Thr Gln Glu Thr Arg Glu 705 710 715 720 Lys Asp Leu Gln Lys Met Tyr Ser Lys Leu Ser Asn Lys Gln Trp Lys 725 730 735 Leu Ser Gln Ile Glu Ile His Asp Ala Ala Ser Thr Thr Ser Ala Pro 740 745 750 Ile Thr Tyr 755 25 791 PRT Drosophila melanogaster 25 Met Lys Tyr Gly Lys Asn Gln Trp Ser Arg Ile Ala Ser Leu Leu His 1 5 10 15 Arg Lys Ser Ala Lys Gln Cys Lys Ala Arg Trp Tyr Glu Trp Leu Asp 20 25 30 Pro Ser Ile Lys Lys Thr Glu Trp Ser Arg Glu Glu Asp Glu Lys Leu 35 40 45 Leu His Leu Ala Lys Leu Met Pro Thr Gln Trp Arg Thr Ile Ala Pro 50 55 60 Ile Ile Gly Arg Thr Ala Ala Gln Cys Leu Glu Arg Tyr Glu Tyr Leu 65 70 75 80 Leu Asp Gln Ala Gln Arg Lys Glu Asp Gly Glu Asp Thr Met Asp Asp 85 90 95 Pro Arg Lys Leu Lys Pro Gly Glu Ile Asp Pro Asn Pro Glu Thr Lys 100 105 110 Pro Ala Arg Pro Asp Pro Lys Asp Met Asp Glu Asp Glu Leu Glu Met 115 120 125 Leu Ser Glu Ala Arg Ala Arg Leu Ala Asn Thr Gln Gly Lys Lys Ala 130 135 140 Lys Arg Lys Ala Arg Glu Lys Gln Leu Glu Glu Ala Arg Arg Leu Ala 145 150 155 160 Thr Leu Gln Lys Arg Arg Glu Leu Arg Ala Ala Gly Ile Gly Ser Gly 165 170 175 Asn Arg Lys Arg Ile Lys Gly Ile Asp Tyr Asn Ala Glu Ile Pro Phe 180 185 190 Glu Lys Arg Pro Ala His Gly Phe Tyr Asp Thr Ser Glu Glu His Leu 195 200 205 Gln Lys Asn Glu Pro Asp Phe Asn Lys Met Arg Gln Gln Asp Leu Asp 210 215 220 Gly Glu Leu Arg Ser Glu Lys Glu Glu Arg Glu Arg Lys Arg Asp Lys 225 230 235 240 Gln Lys Leu Lys Gln Arg Lys Glu Asn Glu Val Pro Thr Ala Met Leu 245 250 255 Gln Asn Met Glu Pro Glu Arg Lys Arg Ser Lys Leu Val Leu Pro Thr 260 265 270 Pro Gln Ile Ser Asp Met Glu Leu Gln Gln Val Val Lys Leu Gly Arg 275 280 285 Ala Ser Glu Met Ala Lys Glu Ile Ala Gly Glu Ser Gly Ile Glu Thr 290 295 300 Thr Asp Ala Leu Leu Ala Asp Tyr Ser Ile Thr Pro Gln Val Ala Ala 305 310 315 320 Thr Pro Arg Thr Pro Ala Pro Tyr Thr Asp Arg Ile Met Gln Glu Ala 325 330 335 Gln Asn Met Met Ala Leu Thr His Thr Glu Thr Pro Leu Lys Gly Gly 340 345 350 Leu Asn Thr Pro Leu His Glu Ser Asp Phe Ser Gly Val Leu Pro Lys 355 360 365 Ala Ala Ser Ile Ala Thr Pro Asn Thr Val Ile Ala Thr Pro Phe Arg 370 375 380 Thr Gln Arg Glu Gly Gly Ala Ala Thr Pro Gly Gly Phe Gln Thr Pro 385 390 395 400 Ser Ser Gly Ala Leu Val Pro Val Lys Gly Ala Gly Gly Ala Thr Gly 405 410 415 Val Val Asn Thr Pro Ala Tyr Val Arg Asp Lys Leu Ser Ile Asn Pro 420 425 430 Glu Glu Ser Met Gly Val Thr Glu Thr Pro Ala His Tyr Lys Asn Tyr 435 440 445 Gln Lys Gln Leu Lys Ser Thr Leu Arg Asp Gly Leu Ser Thr Leu Pro 450 455 460 Ala Pro Arg Asn Asp Tyr Glu Ile Val Val Pro Glu Gln Glu Glu Ser 465 470 475 480 Glu Arg Ile Glu Thr Asn Ser Glu Pro Ala Val Glu Asp Gln Ala Asp 485 490 495 Val Asp Ala Arg Leu Leu Ala Glu Gln Glu Ala Arg Arg Lys Arg Glu 500 505 510 Leu Glu Lys Arg Ser Gln Val Ile Gln Arg Ser Leu Pro Arg Pro Thr 515 520 525 Glu Val Asn Thr Lys Ile Leu Arg Pro Gln Ser Glu Lys Gln Asn Leu 530 535 540 Thr Glu Gln Gln Gln Ala Glu Glu Leu Ile Lys His Glu Met Ile Thr 545 550 555 560 Met Gln Leu Tyr Asp Ser Val Lys Asp Pro Val Pro Gly Gln Ser Gln 565 570 575 His Lys Leu Glu Gln Leu Gln Ser Tyr Phe Lys Ala Asn Pro Tyr Glu 580 585 590 Asp Ile Ser Gln Gln Glu Leu Ala Lys Ala Lys Gln Met Leu Thr Glu 595 600 605 Glu Met Glu Val Val Lys Glu Arg Met Ala His Gly Glu Leu Pro Leu 610 615 620 Asp Val Tyr Ala Gln Val Trp Gln Glu Cys Leu Gly Gln Val Leu Tyr 625 630 635 640 Leu Pro Ser Gln His Arg Tyr Thr Arg Ala Asn Leu Ala Ser Lys Lys 645 650 655 Asp Arg Leu Glu Ser Ala Glu Lys Arg Leu Glu Thr Asn Arg Arg His 660 665 670 Met Ala Lys Glu Ala Lys Arg Cys Gly Lys Ile Glu Lys Lys Leu Lys 675 680 685 Ile Leu Thr Gly Gly Tyr Gln Ala Arg Ala Gln Val Leu Ile Lys Gln 690 695 700 Leu Gln Asp Thr Tyr Gly Gln Ile Glu Gln Asn Ser Val Ser Leu Ser 705 710 715 720 Thr Phe Arg Phe Leu Gly Glu Gln Glu Ala Ile Ala Val Pro Arg Arg 725 730 735 Leu Glu Ser Leu Gln Glu Asp Val Arg Arg Gln Met Asp Arg Glu Lys 740 745 750 Glu Leu Gln Gln Lys Tyr Ala Ser Leu Val Glu Glu Arg Asp Ser Leu 755 760 765 Tyr Ser Gln Ile Glu His Ile Thr Gly Val Arg Pro Thr Ala Gln Gln 770 775 780 Leu Leu Pro Asp Gln Glu Ala 785 790 26 802 PRT Homo sapiens 26 Met Pro Arg Ile Met Ile Lys Gly Gly Val Trp Arg Asn Thr Glu Asp 1 5 10 15 Glu Ile Leu Lys Ala Ala Val Met Lys Tyr Gly Lys Asn Gln Trp Ser 20 25 30 Arg Ile Ala Ser Leu Leu His Arg Lys Ser Ala Lys Gln Cys Lys Ala 35 40 45 Arg Trp Tyr Glu Trp Leu Asp Pro Ser Ile Lys Lys Thr Glu Trp Ser 50 55 60 Arg Glu Glu Glu Glu Lys Leu Leu His Leu Ala Lys Leu Met Pro Thr 65 70 75 80 Gln Trp Arg Thr Ile Ala Pro Ile Ile Gly Arg Thr Ala Ala Gln Cys 85 90 95 Leu Glu His Tyr Glu Phe Leu Leu Asp Lys Ala Ala Gln Arg Asp Asn 100 105 110 Glu Glu Glu Thr Thr Asp Asp Pro Arg Lys Leu Lys Pro Gly Glu Ile 115 120 125 Asp Pro Asn Pro Glu Thr Lys Pro Ala Arg Pro Asp Pro Ile Asp Met 130 135 140 Asp Glu Asp Glu Leu Glu Met Leu Ser Glu Ala Arg Ala Arg Leu Ala 145 150 155 160 Asn Thr Gln Gly Lys Lys Ala Lys Arg Lys Ala Arg Glu Lys Gln Leu 165 170 175 Glu Glu Ala Arg Arg Leu Ala Ala Leu Gln Lys Arg Arg Glu Leu Arg 180 185 190 Ala Ala Gly Ile Glu Ile Gln Lys Lys Arg Lys Arg Lys Arg Gly Val 195 200 205 Asp Tyr Asn Ala Glu Ile Pro Phe Glu Lys Lys Pro Ala Leu Gly Phe 210 215 220 Tyr Asp Thr Ser Glu Glu Asn Tyr Gln Ala Leu Asp Ala Asp Phe Arg 225 230 235 240 Lys Leu Arg Gln Gln Asp Leu Asp Gly Glu Leu Arg Ser Glu Lys Glu 245 250 255 Gly Arg Asp Arg Lys Lys Asp Lys Gln His Leu Lys Arg Lys Lys Glu 260 265 270 Ser Asp Leu Pro Ser Ala Ile Leu Gln Thr Ser Gly Val Ser Glu Phe 275 280 285 Thr Lys Lys Arg Ser Lys Leu Val Leu Pro Ala Pro Gln Ile Ser Asp 290 295 300 Ala Glu Leu Gln Glu Val Val Lys Val Gly Gln Ala Ser Glu Ile Ala 305 310 315 320 Arg Gln Thr Ala Glu Glu Ser Gly Ile Thr Asn Ser Ala Ser Ser Thr 325 330 335 Leu Leu Ser Glu Tyr Asn Val Thr Asn Asn Ser Val Ala Leu Arg Thr 340 345 350 Pro Arg Thr Pro Ala Ser Gln Asp Arg Ile Leu Gln Glu Ala Gln Asn 355 360 365 Leu Met Ala Leu Thr Asn Val Asp Thr Pro Leu Lys Gly Gly Leu Asn 370 375 380 Thr Pro Leu His Glu Ser Asp Phe Ser Gly Val Thr Pro Gln Arg Gln 385 390 395 400 Val Val Gln Thr Pro Asn Thr Val Leu Ser Thr Pro Phe Arg Thr Pro 405 410 415 Ser Asn Gly Ala Glu Gly Leu Thr Pro Arg Ser Gly Thr Thr Pro Lys 420 425 430 Pro Val Ile Asn Ser Thr Pro Gly Arg Thr Pro Leu Arg Asp Lys Leu 435 440 445 Asn Ile Asn Pro Glu Asp Gly Met Ala Asp Tyr Ser Asp Pro Ser Tyr 450 455 460 Val Lys Gln Met Glu Arg Glu Ser Arg Glu His Leu Arg Leu Gly Leu 465 470 475 480 Leu Gly Leu Pro Ala Pro Lys Asn Asp Phe Glu Ile Val Leu Pro Glu 485 490 495 Asn Ala Glu Lys Glu Leu Glu Glu Arg Glu Ile Asp Asp Thr Tyr Ile 500 505 510 Glu Asp Ala Ala Asp Val Asp Ala Arg Lys Gln Ala Ile Arg Asp Ala 515 520 525 Glu Arg Val Lys Glu Met Lys Arg Met His Lys Ala Val Gln Lys Asp 530 535 540 Leu Pro Arg Pro Ser Glu Val Asn Glu Thr Ile Leu Arg Pro Leu Asn 545 550 555 560 Val Glu Pro Pro Leu Thr Asp Leu Gln Lys Ser Glu Glu Leu Ile Lys 565 570 575 Lys Glu Met Ile Thr Met Leu His Tyr Asp Leu Leu His His Pro Tyr 580 585 590 Glu Pro Ser Gly Asn Lys Lys Gly Lys Thr Val Gly Phe Gly Thr Asn 595 600 605 Asn Ser Glu His Ile Thr Tyr Leu Glu His Asn Pro Tyr Glu Lys Phe 610 615 620 Ser Lys Glu Glu Leu Lys Lys Ala Gln Asp Val Leu Val Gln Glu Met 625 630 635 640 Glu Val Val Lys Gln Gly Met Ser His Gly Glu Leu Ser Ser Glu Ala 645 650 655 Tyr Asn Gln Val Trp Glu Glu Cys Tyr Ser Gln Val Leu Tyr Leu Pro 660 665 670 Gly Gln Ser Arg Tyr Thr Arg Ala Asn Leu Ala Ser Lys Lys Asp Arg 675 680 685 Ile Glu Ser Leu Glu Lys Arg Leu Glu Ile Asn Arg Gly His Met Thr 690 695 700 Thr Glu Ala Lys Arg Ala Ala Lys Met Glu Lys Lys Met Lys Ile Leu 705 710 715 720 Leu Gly Gly Tyr Gln Ser Arg Ala Met Gly Leu Met Lys Gln Leu Asn 725 730 735 Asp Leu Trp Asp Gln Ile Glu Gln Ala His Leu Glu Leu Arg Thr Phe 740 745 750 Glu Glu Leu Lys Lys His Glu Asp Ser Ala Ile Pro Arg Arg Leu Glu 755 760 765 Cys Leu Lys Glu Asp Val Gln Arg Gln Gln Glu Arg Glu Lys Glu Leu 770 775 780 Gln His Arg Tyr Ala Asp Leu Leu Leu Glu Lys Glu Thr Leu Lys Ser 785 790 795 800 Lys Phe 27 150 PRT Saccharomyces cerevisiae 27 Pro Glu Phe Lys Asn Asn Pro Gln Ser Ala Ile Asp Asn Lys Tyr Asn 1 5 10 15 Leu Leu Val Ala Asn Ala Ile Asn Lys Glu Pro His Met Val Pro Glu 20 25 30 Asp Thr Val Asp Phe Leu Lys Glu Val Glu Ser Arg Met Gln His Ile 35 40 45 Thr Gln Gly Arg Thr Ser Met Lys Ile Gln Phe Lys Thr Ala Met Pro 50 55 60 Pro Thr Glu Val Leu Leu Glu Ser Ile Gln Ser Lys Val Glu Ser Ile 65 70 75 80 Glu Gln Leu Gln Arg Lys Leu Gln His Val Gln Pro Leu Glu Gln Gln 85 90 95 Asn Asn Glu Met Cys Ser Thr Leu Cys His His Ser Leu Pro Ala Leu 100 105 110 Ile Glu Gly Gln Arg Lys Tyr Tyr Ala Asp Tyr Tyr Ala Tyr Arg Gln 115 120 125 Glu Ile Arg Ser Leu Glu Gly Arg Arg Lys Arg Leu Gln Ala Met Leu 130 135 140 Asn Ser Ser Ser Ser Ile 145 150 28 152 PRT Schizosaccharomyces pombe 28 Lys Glu Ile Gly Gln Leu Glu Ser Asp Asp Tyr Ile Gln Phe Glu Lys 1 5 10 15 Glu Phe Leu Glu Thr Tyr Ser Ala Leu His Asn Thr Ser Ser Leu Leu 20 25 30 Pro Gly Leu Val Ile Tyr Glu Glu Asp Asp Glu Asp Val Glu Ala Ala 35 40 45 Glu Lys Phe Tyr Thr Asn Asp Ile Gln Arg Asp Leu Ala Lys Lys Ala 50 55 60 Leu Glu Cys Asn Lys Leu Glu Asn Arg Val Tyr Asp Leu Val Arg Ser 65 70 75 80 Ser Tyr Glu Gln Arg Asn Phe Leu Ile Lys Lys Ile Ser His Ala Trp 85 90 95 Lys Ala Leu Gln Thr Glu Arg Lys Asn Leu Thr Cys Tyr Glu Phe Leu 100 105 110 Tyr Asn Gln Glu Arg Leu Ala Leu Pro Asn Arg Leu Glu Ala Ala Glu 115 120 125 Ile Glu Leu Ser Lys Met Gln Gln Ile Glu Ala Tyr Ala Gln Gln Asp 130 135 140 Tyr Ala Arg Val Thr Gly Gln Asn 145 150 29 154 PRT Arabidopsis thaliana 29 Ala Ala Phe Gln Glu Glu Met Glu Asn Val Arg Lys Lys Met Glu Glu 1 5 10 15 Asp Glu Lys Lys Ala Glu His Met Lys Ala Lys Tyr Lys Thr Tyr Thr 20 25 30 Lys Gly His Glu Arg Arg Ala Glu Thr Val Trp Thr Gln Ile Glu Ala 35 40 45 Thr Leu Lys Gln Ala Glu Ile Gly Gly Thr Glu Val Glu Cys Phe Lys 50 55 60 Ala Leu Lys Arg Gln Glu Glu Met Ala Ala Ser Phe Arg Lys Lys Asn 65 70 75 80 Leu Gln Glu Glu Val Ile Lys Gln Lys Glu Thr Glu Ser Lys Leu Gln 85 90 95 Thr Arg Tyr Gly Asn Met Leu Ala Met Val Glu Lys Ala Glu Glu Ile 100 105 110 Met Val Gly Phe Arg Ala Gln Ala Leu Lys Lys Gln Glu Asp Val Glu 115 120 125 Asp Ser His Lys Leu Lys Glu Ala Lys Leu Ala Thr Gly Glu Glu Glu 130 135 140 Asp Ile Ala Ile Ala Met Glu Ala Ser Ala 145 150 30 151 PRT Caenorhabditis elegans 30 Cys Thr Ser Glu Ile Ile Leu Ser Lys Asp Lys Phe Thr Arg Ile Ala 1 5 10 15 Ile Leu Pro Arg Glu Glu Gln Met Lys Ala Leu Asn Asp Glu Phe Gln 20 25 30 Met Tyr Arg Gly Trp Met Asn Gln Arg Ala Lys Arg Ala Ala Lys Val 35 40 45 Glu Lys Lys Leu Arg Val Lys Leu Gly Gly Tyr Gln Ala Ile His Asp 50 55 60 Lys Leu Cys Lys Lys Tyr Gln Glu Val Thr Thr Glu Ile Glu Met Ala 65 70 75 80 Asn Ile Glu Lys Lys Thr Phe Glu Arg Leu Gly Glu His Glu Leu Lys 85 90 95 Ala Ile Asn Lys Arg Val Gly Arg Leu Gln Gln Glu Val Thr Thr Gln 100 105 110 Glu Thr Arg Glu Lys Asp Leu Gln Lys Met Tyr Ser Lys Leu Ser Asn 115 120 125 Lys Gln Trp Lys Leu Ser Gln Ile Glu Ile His Asp Ala Ala Ser Thr 130 135 140 Thr Ser Ala Pro Ile Thr Tyr 145 150 31 152 PRT Drosophila melanogaster 31 Tyr Leu Pro Ser Gln His Arg Tyr Thr Arg Ala Asn Leu Ala Ser Lys 1 5 10 15 Lys Asp Arg Leu Glu Ser Ala Glu Lys Arg Leu Glu Thr Asn Arg Arg 20 25 30 His Met Ala Lys Glu Ala Lys Arg Cys Gly Lys Ile Glu Lys Lys Leu 35 40 45 Lys Ile Leu Thr Gly Gly Tyr Gln Ala Arg Ala Gln Val Leu Ile Lys 50 55 60 Gln Leu Gln Asp Thr Tyr Gly Gln Ile Glu Gln Asn Ser Val Ser Leu 65 70 75 80 Ser Thr Phe Arg Phe Leu Gly Glu Gln Glu Ala Ile Ala Val Pro Arg 85 90 95 Arg Leu Glu Ser Leu Gln Glu Asp Val Arg Arg Gln Met Asp Arg Glu 100 105 110 Lys Glu Leu Gln Gln Lys Tyr Ala Ser Leu Val Glu Glu Arg Asp Ser 115 120 125 Leu Tyr Ser Gln Ile Glu His Ile Thr Gly Val Arg Pro Thr Ala Gln 130 135 140 Gln Leu Leu Pro Asp Gln Glu Ala 145 150 32 151 PRT Homo sapiens 32 Leu Ser Ser Glu Ala Tyr Asn Gln Val Trp Glu Glu Cys Tyr Ser Gln 1 5 10 15 Val Leu Tyr Leu Pro Gly Gln Ser Arg Tyr Thr Arg Ala Asn Leu Ala 20 25 30 Ser Lys Lys Asp Arg Ile Glu Ser Leu Glu Lys Arg Leu Glu Ile Asn 35 40 45 Arg Gly His Met Thr Thr Glu Ala Lys Arg Ala Ala Lys Met Glu Lys 50 55 60 Lys Met Lys Ile Leu Leu Gly Gly Tyr Gln Ser Arg Ala Met Gly Leu 65 70 75 80 Met Lys Gln Leu Asn Asp Leu Trp Asp Gln Ile Glu Gln Ala His Leu 85 90 95 Glu Leu Arg Thr Phe Glu Glu Leu Lys Lys His Glu Asp Ser Ala Ile 100 105 110 Pro Arg Arg Leu Glu Cys Leu Lys Glu Asp Val Gln Arg Gln Gln Glu 115 120 125 Arg Glu Lys Glu Leu Gln His Arg Tyr Ala Asp Leu Leu Leu Glu Lys 130 135 140 Glu Thr Leu Lys Ser Lys Phe 145 150 33 451 PRT Saccharomyces cerevisiae 33 Met Asp Gly Asn Asp His Lys Val Glu Asn Leu Gly Asp Val Asp Lys 1 5 10 15 Phe Tyr Ser Arg Ile Arg Trp Asn Asn Gln Phe Ser Tyr Met Ala Thr 20 25 30 Leu Pro Pro His Leu Gln Ser Glu Met Glu Gly Gln Lys Ser Leu Leu 35 40 45 Met Arg Tyr Asp Thr Tyr Arg Lys Glu Ser Ser Ser Phe Ser Gly Glu 50 55 60 Gly Lys Lys Val Thr Leu Gln His Val Pro Thr Asp Phe Ser Glu Ala 65 70 75 80 Ser Gln Ala Val Ile Ser Lys Lys Asp His Asp Thr His Ala Ser Ala 85 90 95 Phe Val Asn Lys Ile Phe Gln Pro Glu Val Ala Glu Glu Leu Ile Val 100 105 110 Asn Arg Tyr Glu Lys Leu Leu Ser Gln Arg Pro Glu Trp His Ala Pro 115 120 125 Trp Lys Leu Ser Arg Val Ile Asn Gly His Leu Gly Trp Val Arg Cys 130 135 140 Val Ala Ile Asp Pro Val Asp Asn Glu Trp Phe Ile Thr Gly Ser Asn 145 150 155 160 Asp Thr Thr Met Lys Val Trp Asp Leu Ala Thr Gly Lys Leu Lys Thr 165 170 175 Thr Leu Ala Gly His Val Met Thr Val Arg Asp Val Ala Val Ser Asp 180 185 190 Arg His Pro Tyr Leu Phe Ser Val Ser Glu Asp Lys Thr Val Lys Cys 195 200 205 Trp Asp Leu Glu Lys Asn Gln Ile Ile Arg Asp Tyr Tyr Gly His Leu 210 215 220 Ser Gly Val Arg Thr Val Ser Ile His Pro Thr Leu Asp Leu Ile Ala 225 230 235 240 Thr Ala Gly Arg Asp Ser Val Ile Lys Leu Trp Asp Met Arg Thr Arg 245 250 255 Ile Pro Val Ile Thr Leu Val Gly His Lys Gly Pro Ile Asn Gln Val 260 265 270 Gln Cys Thr Pro Val Asp Pro Gln Val Val Ser Ser Ser Thr Asp Ala 275 280 285 Thr Val Arg Leu Trp Asp Val Val Ala Gly Lys Thr Met Lys Val Leu 290 295 300 Thr His His Lys Arg Ser Val Arg Ala Thr Ala Leu His Pro Lys Glu 305 310 315 320 Phe Ser Val Ala Ser Ala Cys Thr Asp Asp Ile Arg Ser Trp Gly Leu 325 330 335 Ala Glu Gly Ser Leu Leu Thr Asn Phe Glu Ser Glu Lys Thr Gly Ile 340 345 350 Ile Asn Thr Leu Ser Ile Asn Gln Asp Asp Val Leu Phe Ala Gly Gly 355 360 365 Asp Asn Gly Val Leu Ser Phe Tyr Asp Tyr Lys Ser Gly His Lys Tyr 370 375 380 Gln Ser Leu Ala Thr Arg Glu Met Val Gly Ser Leu Glu Gly Glu Arg 385 390 395 400 Ser Val Leu Cys Ser Thr Phe Asp Lys Thr Gly Leu Arg Leu Ile Thr 405 410 415 Gly Glu Ala Asp Lys Ser Ile Lys Ile Trp Lys Gln Asp Glu Thr Ala 420 425 430 Thr Lys Glu Ser Glu Pro Gly Leu Ala Trp Asn Pro Asn Leu Ser Ala 435 440 445 Lys Arg Phe 450 34 486 PRT Arabidopsis thaliana 34 Met Pro Ala Pro Thr Thr Glu Ile Glu Pro Ile Glu Ala Gln Ser Leu 1 5 10 15 Lys Lys Leu Ser Leu Lys Ser Leu Lys Arg Ser Leu Glu Leu Phe Ser 20 25 30 Pro Val His Gly Gln Phe Pro Pro Pro Asp Pro Glu Ala Lys Gln Ile 35 40 45 Arg Leu Ser His Lys Met Lys Val Ala Phe Gly Gly Val Glu Pro Val 50 55 60 Val Ser Gln Pro Pro Arg Gln Pro Asp Arg Ile Asn Glu Gln Pro Gly 65 70 75 80 Pro Ser Asn Ala Leu Ser Leu Ala Ala Pro Glu Gly Ser Lys Ser Thr 85 90 95 Gln Lys Gly Ala Thr Glu Ser Ala Ile Val Val Gly Pro Thr Leu Leu 100 105 110 Arg Pro Ile Leu Pro Lys Gly Leu Asn Tyr Thr Gly Ser Ser Gly Lys 115 120 125 Ser Thr Thr Ile Ile Pro Ala Asn Val Ser Ser Tyr Gln Arg Asn Leu 130 135 140 Ser Thr Ala Ala Leu Met Glu Arg Ile Pro Ser Arg Trp Pro Arg Pro 145 150 155 160 Glu Trp His Ala Pro Trp Lys Asn Tyr Arg Val Ile Gln Gly His Leu 165 170 175 Gly Trp Val Arg Ser Val Ala Phe Asp Pro Ser Asn Glu Trp Phe Cys 180 185 190 Thr Gly Ser Ala Asp Arg Thr Ile Lys Ile Trp Asp Val Ala Thr Gly 195 200 205 Val Leu Lys Leu Thr Leu Thr Gly His Ile Glu Gln Val Arg Gly Leu 210 215 220 Ala Val Ser Asn Arg His Thr Tyr Met Phe Ser Ala Gly Asp Asp Lys 225 230 235 240 Gln Val Lys Cys Trp Asp Leu Glu Gln Asn Lys Val Ile Arg Ser Tyr 245 250 255 His Gly His Leu Ser Gly Val Tyr Cys Leu Ala Leu His Pro Thr Leu 260 265 270 Asp Val Leu Leu Thr Gly Gly Arg Asp Ser Val Cys Arg Val Trp Asp 275 280 285 Ile Arg Thr Lys Met Gln Ile Phe Ala Leu Ser Gly His Asp Asn Thr 290 295 300 Val Cys Ser Val Phe Thr Arg Pro Thr Asp Pro Gln Val Val Thr Gly 305 310 315 320 Ser His Asp Thr Thr Ile Lys Phe Trp Asp Leu Arg Tyr Gly Lys Thr 325 330 335 Met Ser Thr Leu Thr His His Lys Lys Ser Val Arg Ala Met Thr Leu 340 345 350 His Pro Lys Glu Asn Ala Phe Ala Ser Ala Ser Ala Asp Asn Thr Lys 355 360 365 Lys Phe Ser Leu Pro Lys Gly Glu Phe Cys His Asn Met Leu Ser Gln 370 375 380 Gln Lys Thr Ile Ile Asn Ala Met Ala Val Asn Glu Asp Gly Val Met 385 390 395 400 Val Thr Gly Gly Asp Asn Gly Ser Ile Trp Phe Trp Asp Trp Lys Ser 405 410 415 Gly His Ser Phe Gln Gln Ser Glu Thr Ile Val Gln Pro Gly Ser Leu 420 425 430 Glu Ser Glu Ala Gly Ile Tyr Ala Ala Cys Tyr Asp Asn Thr Gly Ser 435 440 445 Arg Leu Val Thr Cys Glu Ala Asp Lys Thr Ile Lys Met Trp Lys Glu 450 455 460 Asp Glu Asn Ala Thr Pro Glu Thr His Pro Ile Asn Phe Lys Pro Pro 465 470 475 480 Lys Glu Ile Arg Arg Phe 485 35 494 PRT Caenorhabditis elegans 35 Met Ser Ala Ser Val Ser Asp Pro Tyr Glu Gln Met Pro Ala Ala Pro 1 5 10 15 Thr Asp Asp Asp Leu Glu Asp Lys Pro Glu Ala Asp Lys Lys Ala Leu 20 25 30 Leu Asn Gln Val Phe Lys Ser Leu Lys Arg Ala Gln Asp Leu Phe Tyr 35 40 45 His Asp Tyr Ala Gln Pro Pro Pro Met Pro Glu Glu Asn Asp Ser Leu 50 55 60 Ile Arg Ser Met Lys Arg Lys His Glu Tyr Gly Asn Val Ile Lys Lys 65 70 75 80 Val Glu Glu Met Lys Val Arg Arg Glu Asn Glu Met Leu Ala Leu Pro 85 90 95 Thr Ser Gln Pro Met His Gly Thr Gly Ser Val Ile Ala Ser Ala Gly 100 105 110 Thr Pro Leu Ala Ile Thr Asp Gly Ser Gly Lys Leu Val Asn Gln Gln 115 120 125 Gln Gly Ser Ala Lys Ser Gly Thr Leu Leu Pro Leu Val Pro Leu Gly 130 135 140 Asn Ser Ser Lys Gly Glu Asp Asn Thr Thr Arg Ser Leu Leu Pro Ser 145 150 155 160 Lys Ala Pro Met Met Met Lys Pro Lys Trp His Ala Pro Trp Lys Leu 165 170 175 Tyr Arg Val Ala Ser Gly His Thr Gly Trp Val Arg Ala Val Asp Val 180 185 190 Glu Pro Gly Asn Gln Trp Phe Ala Ser Gly Gly Ala Asp Arg Ile Ile 195 200 205 Lys Ile Trp Asp Leu Ala Ser Gly Gln Leu Lys Leu Ser Leu Thr Gly 210 215 220 His Ile Ser Ser Val Arg Ala Val Lys Val Ser Pro Arg His Pro Phe 225 230 235 240 Leu Phe Ser Gly Gly Glu Asp Lys Gln Val Lys Cys Trp Asp Leu Glu 245 250 255 Tyr Asn Lys Val Ile Arg His Tyr His Gly His Leu Ser Ala Val Gln 260 265 270 Ala Leu Ser Val His Pro Ser Leu Asp Val Leu Val Thr Cys Ala Arg 275 280 285 Asp Ser Thr Ala Arg Val Trp Asp Met Arg Thr Lys Ala Gln Val His 290 295 300 Cys Phe Ala Gly His Thr Asn Thr Val Ala Asp Val Val Cys Gln Ser 305 310 315 320 Val Asp Pro Gln Val Ile Thr Ala Ser His Asp Ala Thr Val Arg Leu 325 330 335 Trp Asp Leu Ala Ala Gly Arg Ser Met Cys Thr Leu Thr His His Lys 340 345 350 Lys Ser Val Arg Ala Leu Thr Ile His Pro Arg Leu Asn Met Phe Ala 355 360 365 Ser Ala Ser Pro Asp Asn Ile Lys Gln Trp Lys Leu Pro Lys Gly Glu 370 375 380 Phe Met Gln Asn Leu Ser Gly His Asn Ala Ile Ile Asn Thr Leu Ser 385 390 395 400 Ser Asn Asp Asp Gly Val Val Val Ser Gly Ala Asp Asn Gly Ser Leu 405 410 415 Cys Phe Trp Asp Trp Arg Ser Gly Phe Cys Phe Gln Lys Ile Gln Thr 420 425 430 Lys Pro Gln Pro Gly Ser Ile Glu Ser Glu Ala Gly Ile Tyr Ala Ser 435 440 445 Cys Phe Asp Lys Thr Gly Leu Arg Leu Ile Thr Ala Glu Ala Asp Lys 450 455 460 Thr Ile Lys Met Tyr Lys Glu Asp Asp Glu Ala Thr Glu Glu Ser His 465 470 475 480 Pro Ile Val Trp Arg Pro Glu Ile Val Lys Lys Lys Ala Tyr 485 490 36 514 PRT Homo sapiens 36 Met Val Glu Glu Val Gln Lys His Ser Val His Thr Leu Val Phe Arg 1 5 10 15 Ser Leu Lys Arg Thr His Asp Met Phe Val Ala Asp Asn Gly Lys Pro 20 25 30 Val Pro Leu Asp Glu Glu Ser His Lys Arg Lys Met Ala Ile Lys Leu 35 40 45 Arg Asn Glu Tyr Gly Pro Val Leu His Met Pro Thr Ser Lys Glu Asn 50 55 60 Leu Lys Glu Lys Gly Pro Gln Asn Ala Thr Asp Ser Tyr Val His Lys 65 70 75 80 Gln Tyr Pro Ala Asn Gln Gly Gln Glu Val Glu Tyr Phe Val Ala Gly 85 90 95 Thr His Pro Tyr Pro Pro Gly Pro Gly Val Ala Leu Thr Ala Asp Thr 100 105 110 Lys Ile Gln Arg Met Pro Ser Glu Ser Ala Ala Gln Ser Leu Ala Val 115 120 125 Ala Leu Pro Leu Gln Thr Lys Ala Asp Ala Asn Arg Thr Ala Pro Ser 130 135 140 Gly Ser Glu Tyr Arg His Pro Gly Ala Ser Asp Arg Pro Gln Pro Thr 145 150 155 160 Ala Met Asn Ser Ile Val Met Glu Thr Gly Asn Thr Lys Asn Ser Ala 165 170 175 Leu Met Ala Lys Lys Ala Pro Thr Met Pro Lys Pro Gln Trp His Pro 180 185 190 Pro Trp Lys Leu Tyr Arg Val Ile Ser Gly His Leu Gly Trp Val Arg 195 200 205 Cys Ile Ala Val Glu Pro Gly Asn Gln Trp Phe Val Thr Gly Ser Ala 210 215 220 Asp Arg Thr Ile Lys Ile Trp Asp Leu Ala Ser Gly Lys Leu Lys Leu 225 230 235 240 Ser Leu Thr Gly His Ile Ser Thr Val Arg Gly Val Ile Val Ser Thr 245 250 255 Arg Ser Pro Tyr Leu Phe Ser Cys Gly Glu Asp Lys Gln Val Lys Cys 260 265 270 Trp Asp Leu Glu Tyr Asn Lys Val Ile Arg His Tyr His Gly His Leu 275 280 285 Ser Ala Val Tyr Gly Leu Asp Leu His Pro Thr Ile Asp Val Leu Val 290 295 300 Thr Cys Ser Arg Asp Ser Thr Ala Arg Ile Trp Asp Val Arg Thr Lys 305 310 315 320 Ala Ser Val His Thr Leu Ser Gly His Thr Asn Ala Val Ala Thr Val 325 330 335 Arg Cys Gln Ala Ala Glu Pro Gln Ile Ile Thr Gly Ser His Asp Thr 340 345 350 Thr Ile Arg Leu Trp Asp Leu Val Ala Gly Lys Thr Arg Val Thr Leu 355 360 365 Thr Asn His Lys Lys Ser Val Arg Ala Val Val Leu His Pro Arg His 370 375 380 Tyr Thr Phe Ala Ser Gly Ser Pro Asp Asn Ile Lys Gln Trp Lys Phe 385 390 395 400 Pro Asp Gly Ser Phe Ile Gln Asn Leu Ser Gly His Asn Ala Ile Ile 405 410 415 Asn Thr Leu Thr Val Asn Ser Asp Gly Val Leu Val Ser Gly Ala Asp 420 425 430 Asn Gly Thr Met His Leu Trp Asp Trp Arg Thr Gly Tyr Asn Phe Gln 435 440 445 Arg Val His Ala Ala Val Gln Pro Gly Ser Leu Asp Ser Glu Ser Gly 450 455 460 Ile Phe Ala Cys Ala Phe Asp Gln Ser Glu Ser Arg Leu Leu Thr Ala 465 470 475 480 Glu Ala Asp Lys Thr Ile Lys Val Tyr Arg Glu Asp Asp Thr Ala Thr 485 490 495 Glu Glu Thr His Pro Val Ser Trp Lys Pro Glu Ile Ile Lys Arg Lys 500 505 510 Arg Phe 37 2409 DNA Homo sapiens 37 atgcctcgaa ttatgatcaa ggggggcgta tggaggaata ccgaggatga aattctgaaa 60 gcagcggtaa tgaaatatgg gaaaaatcag tggtctagga ttgcctcatt gctgcataga 120 aaatcagcaa agcagtgcaa agccagatgg tatgaatggc tggatccaag cattaagaag 180 acagaatggt ccagagaaga agaggaaaaa ctcttgcact tggccaagtt gatgccaact 240 cagtggagga ccattgctcc aatcattgga agaacagcgg cccagtgctt agaacactat 300 gaatttcttc tggataaagc tgcccaaaga gacaatgaag aggaaacaac agatgatcca 360 cgaaaactta aacctggaga aatagatcca aatccagaaa caaaaccagc gcggcctgat 420 ccaattgata tggatgagga tgaacttgag atgctttctg aagccagagc ccgcttggct 480 aatactcagg gaaagaaggc caagaggaaa gcaagagaga aacaattgga agaagcaaga 540 cgtcttgctg ccctccaaaa aagaagagaa cttcgagcag ctggcataga aattcagaag 600 aaaagaaaaa ggaagagagg agttgattat aatgccgaaa tcccatttga aaaaaagcct 660 gcccttggtt tttatgatac ttctgaggaa aactaccaag ctcttgacgc agatttcagg 720 aaattaagac aacaggatct tgatggggag ctaagatctg aaaaagaagg aagagataga 780 aaaaaagaca aacagcattt gaaaaggaaa aaagaatctg atttaccatc agctattctt 840 caaactagtg gtgtttctga atttactaaa aagagaagca aactagtact tcctgcccct 900 cagatttcag atgcagaact ccaggaagtt gtaaaagtag gccaagcgag tgaaattgca 960 cgtcaaactg ccgaggaatc tggcataaca aattctgctt ccagtacact tttgtctgag 1020 tacaatgtca ccaacaacag cgttgctctt agaacaccac gaacaccagc ttcccaggac 1080 agaattctgc aggaagccca gaacctcatg gccctcacca atgtggacac cccattgaaa 1140 ggtggactta ataccccatt gcatgagagt gacttctcag gtgtaactcc acagcgacaa 1200 gttgtacaga ctccaaacac agttctctct actccattca ggactccttc taatggagct 1260 gaagggctga ctccccggag tggaacaact cccaaaccag ttattaactc tactccgggt 1320 agaactcctc ttcgagacaa gttaaacatt aatcccgagg atggaatggc agactatagt 1380 gatccctctt acgtgaagca gatggaaaga gaatcccgag aacatctccg tttagggttg 1440 ttgggccttc ctgcccctaa gaatgatttt gaaattgttc taccagaaaa tgccgagaag 1500 gagctggaag aacgtgaaat agatgatact tacattgaag atgctgctga tgtggatgct 1560 cgaaagcagg ccatacgaga tgcagagcgt gtaaaggaaa tgaaacgaat gcataaagct 1620 gtccagaaag atctgccaag accatcagaa gtaaatgaaa ctattctaag acccttaaat 1680 gtagaaccgc ctttaacaga tttacagaaa agtgaagaac taatcaaaaa agaaatgatc 1740 acaatgcttc attatgacct tctacatcac ccttatgaac catctggaaa taaaaaaggc 1800 aaaactgtag ggtttggtac caataattca gagcacatta cctatctgga acataatcct 1860 tatgaaaagt tctccaaaga agagctgaaa aaggcccagg atgttttggt gcaggagatg 1920 gaagtggtta aacaaggaat gagccatgga gagctctcaa gtgaagctta taaccaggtg 1980 tgggaagaat gctacagtca agttttatat cttcctgggc agagccgcta cacacgggcc 2040 aatctggcta gtaaaaagga cagaattgaa tcacttgaaa agaggctcga gataaacagg 2100 ggtcacatga cgacagaagc caagagggct gcaaagatgg aaaagaagat gaaaattttg 2160 cttgggggtt accagtctcg tgctatgggg ctcatgaaac agttgaatga cttatgggac 2220 caaattgaac aggctcactt ggagttacgc acttttgaag aactcaagaa acatgaagat 2280 tctgctattc cccggaggct agagtgtcta aaagaagacg ttcagcgaca acaagaaaga 2340 gaaaaggaac ttcaacatag atatgctgat ttgctgctgg agaaagagac tttaaagtca 2400 aaattctga 2409 38 1773 DNA Saccharomyces cerevisiae 38 atgccccccg taccaatata cgtgaaaggc ggtgtatgga ccaatgtgga ggatcagatt 60 cttaaagcgg ctgtacaaaa atacggaact catcagtgga gcaaagtagc atcccttttg 120 cagaaaaaga ctgccaggca gagtgaatta aggtggaatg aatatttaaa tccaaagttg 180 aattttacag agttctcgaa ggaggaggat gcccaacttc tagatcttgc aagagagctg 240 cctaatcagt ggaggaccat agctgatatg atggccaggc ctgcacaggt ctgcgtcgaa 300 agatataata ggctattaga aagtgaagac agtggagggg ctgcgttaag tacaggagtt 360 actgacttga aagccgggga tattaatcct aacgctgaaa ctcaaatggc tagaccagat 420 aatggtgatt tggaagatga ggaaaaggaa atgcttgctg aagctagggc tcgtctgtta 480 aatacccaag gtaagaaggc tacaagaaag attagagagc ggatgctcga agaatcaaaa 540 cgcattgctg aactacaaaa gaggcgtgag ctaaagcaag caggaattaa tgttgccatt 600 aagaaaccga aaaaaaaata cggcaccgac attgattaca atgaagatat agtatatgaa 660 caagctccca tgccaggtat atatgacacg tccactgaag accgccagat aaaaaagaag 720 tttgagcagt ttgagagaaa agtcaacaga aaaggtttgg atggtaataa ggataagcca 780 agtaaaaaaa ataaggacaa aaaaagaaaa cacgatgaga acgaacacgt tgagaaagca 840 gcactgggtg aatctactac attgacggat gagtataaaa aaccaaaact tatactatct 900 gcaccaggaa cgaaacaggg aaaagtcacc tataaaaaaa agctagaaag caaaagacaa 960 aaactaatcg aggcacaagc aactggcact gtgttgacac caaaagaact actaccccac 1020 gactccggcc aagaagataa tgaacgcagt aatataaaga gtggtaaaca gctaaaatca 1080 cgcatacgaa aatttttagt gcaaatgttc gcatctttgc ctagtcccaa gaacgatttc 1140 gaaattgtat taagtgaaga cgagaaagaa gaagatgcag agatagcgga atacgagaaa 1200 gaatttgaaa atgaaagagc gatgaatgaa gaggacaact tcatagaacc accatctcaa 1260 aatgatgcgc cacgcgtctc attagtagcc gttccattag cttactcaac gctacccata 1320 ccagaattca aaaacaatcc gcagtccgcg attgacaata agtacaactt gctagtcgcg 1380 aacgccataa acaaagaacc tcacatggta ccagaagata cggtagattt tctcaaagag 1440 gtggagtcgc gtatgcagca tataacccaa gggcgcactt ccatgaaaat acaattcaaa 1500 acagcaatgc ccccaactga ggttcttctg gaatcgatcc aatcaaaagt ggagtctatt 1560 gaacagttac agcgtaaact acaacatgtg caaccactgg aacaacagaa taacgagatg 1620 tgcagtaccc tctgccatca cagcctgccc gctttgattg aagggcaacg caagtactac 1680 gctgattact acgcctaccg acaagagata cgatcgcttg agggtcgtag aaagcgtctt 1740 caagccatgc taaattcttc ttcttccata tag 1773 39 1740 DNA Schizosaccharomyces pombe 39 gctttctgac aattgtcagg gttttggcga atatttagaa aatggttgtt ttaaaaggag 60 gtgcctggaa aaatacagag gatgaaatct taaaggctgc tgtcagtaaa tacggtaaaa 120 accaatgggc ccgcataagt tcattgctgg ttcgcaaaac tcctaaacaa tgtaaagctc 180 gttggtatga atggatcgat ccaagcatta aaaagactga atggagtcgt gaagaggacg 240 aaaaattatt acacttagct aagttacttc ctacacagtg gcggacgatt gctccaattg 300 taggtcggac ggccactcaa tgtttagaac gctatcaaaa acttcttgat gatttggaag 360 cgaaagagaa cgagcagttg ggattgatca gtggagaagg tgcagaagca gctgcgcctg 420 ttaacgatcc aaattcccgg cttcgttttg gcgaagcaga gcccaattta gaaaccctac 480 ctgcactccc tgatgccatt gacatggatg aagacgaaaa agagatgttg agtgaagcac 540 gtgcacgttt agcaaacaca caaggaaaga aagccaaacg aaaggataga gaaaagcagc 600 ttgaattaac tagaagattg tcacatctcc aaaagcgaag agaattgaag gcagctggaa 660 tcaatataaa gctcttccgt cgaaagaaga atgaaatgga ttataacgct tctattccat 720 ttgaaaaaaa gccagcgatt ggtttttatg atacctcaga agaggacagg caaaattttc 780 gggaaaagcg agaagcggac cagaagataa ttgaaaatgg aatacggaat aatgaaatgg 840 aatccgaagg tcgaaaattt ggtcattttg aaaagccaaa acctattgat agagtaaaaa 900 agcccaacaa agatgcccaa gaagaaaaaa tgcgacgtct tgccgaggct gagcagatga 960 gcaagaggcg gaagttgaat ttacctagtc ctactgtgtc tcaagatgaa ctggataaag 1020 tagtgaaact aggctttgca ggcgatcgtg ctcgcgctat gactgatacg actccagatg 1080 ctaattacag tactaatttg ttaggaaagt atacacaaat tgaacgagct actccattga 1140 gaacaccaat tagtggtgaa cttgagggaa gagaggattc agttacaatt gaagttagaa 1200 atcaattgat gaggaaccgc gaacaatctt ctctcttggg tcaggaaagt atacctttac 1260 aacctggtgg tactggttac acaggagtta ctcccagtca tgcagctaat ggctcagctt 1320 tggcagcacc tcaagcaact ccttttagaa caccacgtga cacattttct attaatgcag 1380 ctgcggagcg agcaggacga ttagcaagtg aaagagaaaa taaaattcga ttgaaggctt 1440 tgcgagaatt gcttgcaaaa ctacctaaac ctaaaaacga ctatgaacta atggagcctc 1500 gatttgcgga cgaaactgat gttgaagcta ctgttggagt gcttgaagaa gacgcaacag 1560 accgagaacg tcgtatccaa gaacgtattg cagaaaaaga aaggttggca aaagcgagga 1620 ggtcacaggt tattcaaaga gatttgattc gaccatctgt aacacaacca gaaaaatgga 1680 agcgttcact tgaaaatgaa gatccgactg caaatgtttt attgaaagaa atgattgctt 1740 40 1548 DNA Homo sapiens 40 atggtcgagg aggtacagaa acattctgta cacacccttg tgttcaggtc gttgaagagg 60 acccatgaca tgtttgtagc tgataatgga aaacctgtgc ctttagatga agagagtcac 120 aaacgaaaaa tggcaatcaa gcttcgtaat gagtatggtc ctgtgttgca tatgcctact 180 tcaaaagaaa atcttaaaga gaagggtcct cagaatgcaa cggattcata tgttcataaa 240 cagtaccctg ccaatcaagg acaagaagtt gaatactttg tggcaggtac acatccatac 300 ccaccaggac ctggggttgc tttgacagca gatactaaga tccagagaat gccaagtgaa 360 tcagctgcac agtccttagc ggtggcatta cctttgcaga ccaaggctga tgcaaatcgt 420 actgccccta gtggaagtga ataccgacat cctggggctt ctgaccgtcc acagcctaca 480 gcgatgaatt caattgtcat ggagactggc aataccaaga actctgcact gatggctaaa 540 aaagccccta caatgccaaa accccagtgg cacccaccgt ggaaactcta cagggttatc 600 agtgggcatc ttggctgggt tcgatgtatt gctgtggaac ctggaaatca gtggtttgtt 660 actggatctg ctgacagaac tataaagatc tgggacttgg ctagtggcaa attaaaactg 720 tcattgactg ggcatattag tactgtgcgg ggcgtgatag taagcacaag gagcccatat 780 ctgttctctt gtggagaaga caaacaagtg aaatgctggg atctcgaata caataaggtt 840 atacggcatt atcatggaca tttaagtgca gtgtatggtt tggatttgca cccgacaatc 900 gatgtgttgg taacctgtag tcgagattca actgcacgga tttgggatgt gagaactaaa 960 gccagtgtac acacattatc tggacataca aatgcagttg ctacagtgag atgtcaggct 1020 gcagaaccac aaattattac aggaagccat gatactacaa ttcgattatg ggatctggtg 1080 gctggaaaaa caagagtgac attaacaaat cacaaaaaat cagttagggc tgtggtttta 1140 catccaagac attacacatt tgcatctggt tctccagata acataaagca gtggaaattc 1200 cctgatggaa gtttcattca aaatctttcc ggtcataatg ctattattaa cacattgacg 1260 gtaaattctg atggagtgct tgtatctgga gctgacaatg gcaccatgca tctttgggac 1320 tggagaactg gctacaattt tcagagagtt cacgcagctg tgcaacctgg gtctttggac 1380 agtgaatcag gaatatttgc ttgtgctttt gatcagtctg aaagtcgatt actaacagct 1440 gaagctgata aaaccattaa agtatacaga gaggatgaca cagccacaga agaaactcat 1500 ccagtcagct ggaaaccaga aattatcaag agaaagagat tttaatga 1548 41 1356 DNA Saccharomyces cerevisiae 41 atggacggaa atgatcacaa agtcgaaaat ttaggagatg tagacaaatt ttattccaga 60 atacgctgga ataaccaatt ttcatatatg gccactctgc cgccccacct acaaagcgaa 120 atggaaggtc agaaatcatt gctaatgcga tatgatactt ataggaagga aagttcttct 180 tttagtggtg aaggcaagaa agttactctg cagcatgttc ctacagattt ttcagaagca 240 tcacaagcag tgattagcaa gaaagatcac gatacgcatg catctgcttt tgtgaataaa 300 attttccaac cagaggttgc tgaagaactt atagttaatc gatacgaaaa acttctgtca 360 caaaggccgg aatggcatgc accctggaaa ctttcacgcg ttatcaatgg ccatcttgga 420 tgggtacgat gcgttgcaat cgatcctgtt gacaacgaat ggttcatcac cggaagtaat 480 gatacgacaa tgaaagtttg ggatcttgca acaggaaaat taaaaactac cttagcaggg 540 catgtaatga cagtgagaga cgttgctgtg tcagatcgac atccttattt attttctgtt 600 agtgaagata agacggtcaa atgctgggac ctagagaaaa accaaattat tagagattac 660 tatggacatt tatcgggggt tcgtacggtg agcatacatc caacgctgga tctcatagct 720 accgcaggcc gagatagcgt tatcaaactc tgggatatga gaaccagaat acctgttatt 780 acactagttg ggcataaggg tccaatcaat caagtacagt gtactccagt agaccctcaa 840 gtggtgagtt catcgactga tgctacggta aggttatggg atgtagttgc tgggaaaaca 900 atgaaagttc taacacatca taagaggtct gtgagagcta cagcgttgca tcctaaggag 960 ttttcggtgg cttctgcgtg tactgatgac atcagatcat ggggattagc agaggggtct 1020 ttactcacca attttgagtc tgaaaagaca ggcataatca atactttaag cattaatcaa 1080 gatgatgtat tattcgctgg cggtgacaat ggtgtgcttt ccttttatga ttataagtct 1140 ggtcacaaat accaatcgtt ggccacgaga gaaatggtag gctctctgga aggtgaacgg 1200 agtgttcttt gtagcacttt cgataaaaca ggtttaagat taatcactgg agaagcagac 1260 aaaagcataa agatttggaa acaggatgag acggctacaa aagagtcaga accggggcta 1320 gcgtggaacc ccaacttaag cgccaaaaga ttttag 1356 42 2093 DNA Schizosaccharomyces pombe 42 atgacagaag caaaaaacat atcggatgat acagatgtac tttctttgac tacaaatagt 60 cttagaacat caaaaactct ttttggagcc gagtttgggt cagttaccag ttttgacgat 120 actgtagctc aaaatctcaa aagaacatac aaagaacatt tagaatatgg ttctgttctt 180 ggaggaactg ttggaaaacg gaagaaccga cattacgaag aagacactat tggtagtaat 240 gctttgacgg ttagagcaga cagtgaaaac ccttcctccc aagtgatcac caagttttca 300 gatcctaata agaaaatagc agggcaggtt tccatgcaat ctttagaaaa aattaaagga 360 gttcctgaag cagcacatag aattgccgga gaatcccagg cttctctcgt aaagcgcact 420 cttgccgaac agattcgccc tgaatggcat gctccatgga ctcttatgcg tgttattagt 480 ggtcatttgg gttgggttcg atgcgtagat gttgaacccg gtaatcaatg gttttgcacg 540 ggtgctgggg accgcaccat caaaatatgg gacttagcgt ctggagtact taagctaaca 600 ttgactgggc atatcgccac tgtgcgagga ttagcagtat ctccccgtca tccatattta 660 ttttcctgtg gtgaagacaa aatggtaaaa tgctgggacc tcgaaactaa taaagtgatc 720 cgccattatc acgggcatct ttccggagtc tatgccttaa aactccatcc aacacttgac 780 gtccttgtta ccgctggtcg tgatgcagtc gctcgtgttt gggatatgcg cactcgccaa 840 aatgtccatg ttttatcggg ccacaaatcc actgttgctt ctttagccgt tcaagaattc 900 gatcctcaag tagtcacggg ttccatggat tctactatca gattatggga tttagcagct 960 gggaaaacct tgacgacctt gacacatcac aaaaaaactg ttcgtgccct gtctttgcat 1020 ccagatgaat ttacttttgc cagtggctcg tccgacaata tcaaacattg gaaattccct 1080 gaaggcgcat ttatgggtaa ttttgaagga cataatgcaa tcgttaatac tctttcaata 1140 aactcagata atgttatgtt ttctggtgct gataatggaa gcatgtgctt ttgggattgg 1200 aagtctggtc acaaatatca agagcttcaa tctgttgttc aacctggttc attggatagc 1260 gaagctggaa tctttgctag ttcttttgat aaaaccggtt tgcgtctaat tacttgtgag 1320 gctgataaaa gcgtaaagat atacaaacaa gtggacaatg ccacacctga aacacatccc 1380 aatttgccat ggacaccatc aaatcttcgt cggcgatatt aatgatttca tcggacgcca 1440 ttaattatcc gtttggaaat tcaaaagtga aaggaacggc taacaaagtg cctgatttgt 1500 caaatgaaga aattgagagg tgtagattgt tactaaagaa agagataggg caactagaaa 1560 gtgacgatta tatccaattc gagaaggaat ttttggaaac gtacagtgca cttcacaaca 1620 cctcaagttt gttgccaggc ttggtaatct acgaggaaga cgatgaagac gttgaagccg 1680 ctgaaaagtt ttatacgaac gacattcaac gagatttagc taagaaagca ttggaatgta 1740 acaagttgga aaatcgggtt tatgatttgg ttagatcttc atatgagcaa cgtaattttt 1800 tgataaagaa aatctcgcat gcttggaagg ctttgcaaac agaaaggaaa aatttaacgt 1860 gctacgaatt tctatacaat caggagcgat tagctctacc taataggctt gaagcagctg 1920 aaatagagct aagcaaaatg caacaaatcg aggcgtatgc tcaacaagat tatgctaggg 1980 ttactggaca aaattaaact tcacttcact ttgttttaaa taattgtcat agcttatcat 2040 tcatagtgta tattatcatg cctgaaataa aacgaaagtt ttataaaaag ata 2093 43 23 PRT Homo sapiens 43 Cys Ser Arg Asp Ser Thr Ala Arg Ile Trp Asp Val Arg Thr Lys Ala 1 5 10 15 Ser Val His Thr Leu Ser Gly 20 

1. A method for identifying a substance capable of modulating an interaction between (i) a CDC5L polypeptide or a homologue thereof, or a derivative thereof, and (ii) a PLRG1 polypeptide, or a homologue thereof, or a derivative thereof, which method comprises: a) providing a CDC5L polypeptide or a homologue, or a derivative thereof, as a first component and a PLRG1 polypeptide or a homologue, or a derivative thereof, as a second component; b) contacting the two components with a test substance under conditions that would permit the two components to interact in the absence of said test substance; and c) determining whether said substance modulates the interaction between the first and second components.
 2. The method according to claim 1 further comprising: d) administering a substance which has been determined to disrupt the interaction between the first and second components to a eukaryotic cell; and e) determining the effect of the substance on the cell.
 3. The method according to claim 1, wherein the CDC5L polypeptide comprises amino acid residues 602-800 of the human sequence or corresponding region from a species specific homologue.
 4. The method according to claim 1, wherein the PLRG1 polypeptide comprises amino acid residues 257-396 of the human sequence or a corresponding region from a species specific homologue.
 5. The method according to claim 1, wherein the CDC5L and/or PLR1 polypeptides are obtained from mammalian, yeast or fungal sources.
 6. The method according to claim 1, wherein said CDC5L and/or PLRG1 polypeptides are recombinantly produced.
 7. A substance capable of modulating an interaction between (i) a CDC5L polypeptide or a homologue thereof, or a derivative thereof, and (ii) PLRG1 or a homologue thereof, or a derivative thereof, identified by a method according to claim 1, for use in treating the human or animal body by therapy or for use in diagnosis.
 8. Use of a substance according to claim 7 for the preparation of a medicament for the prevention or treatment of cancer, or fungal infections.
 9. A substance capable of modulating an interaction between (i) a CDC5L polypeptide or a homologue thereof, or a derivative thereof, and (ii) PLRG1 or a homologue thereof, or a derivatives thereof, identified by a method according to claim 1 for use in regulating mRNA splicing.
 10. Use of the substance according to claim 9 for the manufacture of a medicament for inhibiting protein synthesis by disrupting mRNA splicing.
 11. A method of regulating and/or disrupting the cell cycle in a eukaryotic cell, which method comprises administering to said cell a substance capable of modulating an interaction between (i) a CDC5L polypeptide or a homologue thereof, or a derivative thereof, and (ii) PLRG1 or a homologue thereof, or a derivative thereof.
 12. A peptide comprising the sequence: a) EKKMKILLGGYQ; b) EKKLKILTGGYZ; c) EKKLGKVLGGYD; d) ENKYDIYTKGYQ; e) PYLFSCCEDKQVKCWDLEYNKVIRHYHGHL; or f) PQIITGSHDTTIRLWDLVAGKTRVTLTHNK

for use in inhibiting pre-mRNA splicing.
 13. Use of a peptide according to claim 12 in therapy or diagnosis.
 14. Use of a peptide: a) EKKMKILLGGYQ; b) PYLFSCCEDKQVKCWDLEYNKVIRHYHGHL; or c) PQIITGSHDTTIRLWDLVAGKTRVTLTNHK

for the manufacture of a medicament for treating diseases associated with undesirable pre-mRNA splicing.
 15. The use according to claim 14 wherein said diseases are cancer or psoriasis.
 16. Use of the peptide EKKLKILTGGYZ for the manufacture of a pesticide.
 17. The use according to claim 16 for attacking Drosophila melanogaster.
 18. Use of the peptide EKKLGKVLGGYD for the manufacture of a medicament for treating a fungal infection.
 19. Use of the peptide ENKYDIYTKKGYQ for the manufacture of a medicament for treating a yeast infection.
 20. A peptide comprising the sequence EKKMKILLGGYQ from positions 714-725 of the human CDC5L peptide sequence or corresponding sequence from a species specific homologue for use in inhibiting pre-mRNA splicing.
 21. Use of the peptide according to claim 20 in therapy or diagnosis.
 22. A peptide comprising the sequence: [[e]]a) PYLFSCCEDKQVKCWDLEYNKVIRHYHGHL (residues 259-288); or [[f]]b) PQIITGSHDTTIRLWDLVAGKTRVTLTNHK (residues 343-372)

from the human PLRG1 peptide sequence or corresponding sequence from a species specific homologue for use in inhibiting pre-mRNA splicing.
 23. Use of the peptide according to claim 22 in therapy or diagnosis.
 24. A pharmaceutical formulation comprising the peptide according to claim 12 together with a pharmaceutical acceptable excipient.
 25. A pharmaceutical formulation comprising the peptide according to claim 20 together with a pharmaceutical acceptable excipient.
 26. A pharmaceutical formulation comprising the peptide according to claim 22 together with a pharmaceutical acceptable excipient. 